Ocular-performance-based head impact measurement using a faceguard

ABSTRACT

A faceguard is configured for measuring a human eye muscle movement response. The faceguard is configured for protecting at least one part of a human face and has an aperture for human vision through the faceguard. The faceguard comprises an eye sensor, a head orientation sensor, and an electronic circuit. The eye sensor comprises a video camera and is configured for measuring eyeball movement, pupil size, and/or eyelid movement. The head orientation sensor senses pitch and/or yaw of a person&#39;s head. The electronic circuit is responsive to the eye sensor and the head orientation sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 16/351,326 filed 12 Mar. 2019, which is a Continuation-in-Partof U.S. patent application Ser. No. 16/264,242 filed 31 Jan. 2019. U.S.patent application Ser. No. 16/264,242 is a Continuation-in-Part of U.S.patent application Ser. No. 15/713,418 filed 22 Sep. 2017, which is aContinuation-in-Part of U.S. patent application Ser. No. 15/162,300filed 23 May 2016, which is a Continuation-in-Part of U.S. patentapplication Ser. No. 14/326,335 filed 8 Jul. 2014. U.S. patentapplication Ser. No. 16/264,242 is also a Continuation-in-Part of U.S.patent application Ser. No. 13/749,873 filed 25 Jan. 2013. The entiredisclosures of all of the aforementioned patents and applications areincorporated by reference herein.

FIELD OF INVENTION

Embodiments of the invention(s) disclosed herein relate to systems andmethods that use human ocular performance measurement in combinationwith a face guard. Human ocular performance can be measured usingvestibulo-ocular reflex, ocular saccades, pupillometry, visual pursuittracking, vergence, eye-lid closure, focused position of the eyes,dynamic visual acuity, kinetic visual acuity, virtual retinal stability,retinal image stability, foveal fixation stability and nystagmus.

BACKGROUND

Concussions are a type of traumatic brain injury (TBI) that is sometimescalled a mild traumatic brain injury or a moderate traumatic braininjury and abbreviated as an MTBI. Concussions and the resultant chronictraumatic encephalopathy (CTE) have reached epidemic proportions in theUS. The CDC estimates that as many as 3.8 million sports-relatedconcussions occur in the U.S. each year including professional athletes,amateurs of all levels, and children. There are over 250,000 emergencyroom visits of young people annually for head injuries from sports andrecreation activities. Over 50 million Americans participate in teamsports and all of them are at some level of risk of experiencing aconcussion. Concussions from multiple head blows and the resulting CTEhave caused several professional football players to commit suicides.The US National Football League (NFL) and the scientific communityrecognize that concussions are a major concern for both players and thesport itself. Concussions also occur in college and high schoolfootball, in other sports such as ice hockey and cycling, and inmilitary operations.

Concussions happen in the brain's white matter when forces transmittedfrom a big blow strain nerve cells and their connections, the axons,resulting in changes to the brain such as pruning, synaptic pruning, andmyelination. Linear blunt trauma can happen when falling to the groundand hitting the back of the head. The falling motion propels the brainin a straight line downward. Rotational blunt trauma can occur when aplayer is spun, rolled or turned with the head hitting the object. Thebase of the skull is rough with many internal protuberances. Theseridges can cause trauma to the temporal lobes during rapid deceleration.There is a predicted intracranial pressure wave after a concussive blowwith the positive pressure (coup) to negative pressure (contre-coup)occurring across the brain. A high sheer stress occurs in the centralcore of the brain (e.g. brainstem). Axonal injury occurs withdegeneration/disintegration in discrete regions of the brain. Axonretraction and areas of hemorrhage are noted.

Diffuse axonal injury (DAD occurs from rotational forces. The injury totissue is greatest in areas where the density difference is greatest.For this reason, almost ⅔ of DAI lesions occur at the gray-white matterjunction. Location of injury depends on plane of rotation. The magnitudeof injury depends on the distance from the center of rotation, arc ofrotation, duration and intensity of the force. There are widespreadmetabolic changes (reduced N-Acetylaspartate (NAA)/Creatine (Cr),increased Choline (Cho)/Cr, and reduced NAA/Cho ratios). Early and lateclinical symptoms, including impairments of memory and attention,headache, and alteration of mental status, are the result of neuronaldysfunction. The mechanical insult initiates a complex cascade ofmetabolic events. Starting from neurotoxicity, energetic metabolismdisturbance caused by the initial mitochondrial dysfunction seems to bethe main biochemical explanation for most post-concussive signs andsymptoms. Furthermore, concussed cells enter a peculiar state ofvulnerability, and if a second concussion is sustained while they are inthis state, they may be irreversibly damaged by the occurrence ofswelling. This condition of concussion-induced brain vulnerability isthe basic pathophysiology of the second impact syndrome.

Prior Art Non-Ocular Concussion Assessment Methods and Systems

Current methods concussion assessment methods and systems areinadequate. The techniques used include: (a) questioning the athlete orperson about the incident; (b) a sideline test with brief neurologicexam and follow up with a clinician; and (c) transferring the patient tomedical facility to perform an emergency CT or MRI scan of the head.

Following a witnessed or reported traumatic force to the head, athletesare typically evaluated on the sideline or locker room withinterrogation regarding relevant symptoms. More common symptoms includeheadache, dizziness, difficulty with concentration, confusion and visualdisturbance or photosensitivity. Many also experience nausea,drowsiness, amnesia, irritability or feeling dazed. However, none ofthese symptoms either alone or in combination, are specific forconcussion, and frequently concussions can be undetectable by symptomscreening alone. Such a sideline evaluation is suboptimal. More specifictesting is not readily available for most individuals and a delayedevaluation is the norm. For those seen later by clinicians, theneurologic exam is often normal. While CT scans are effective indetecting acute brain trauma such as hematoma or edema, they are limitedin detecting concussions and other concussion-related symptoms becauseconcussions affect brain function rather than structure. Thus,functional tools, such as functional MRIs (fMRIs) need to be used.

A fMRI is a concussion diagnostic tool used by medical professionals tomeasure the difference between the magnetic states of oxygen-rich andoxygen-poor blood through the use of blood-oxygen-level-dependent (BOLD)contrast techniques. These scans may not be readily available at mosthospitals and the use is limited.

Further, specific clinical laboratory tests with professionalspecialists to interpret the data are not immediately available or evenaccessible to some players. There are presently some tests available forconcussion assessment. Both balance and gait can also be affected in thesetting of concussion, and numerous sideline assessments are intended toevaluate these sensorimotor functions.

The Standardized Assessment of Concussion (SAC) is a brief cognitivetest that specifically evaluates orientation, concentration, and memory.While the test is easy to administer as a sideline screening tool, itsuffers from inadequate sensitivity to justify its use as a stand-alonetest. Furthermore, as with symptom checklists, determined athletes canmanipulate the outcome, either by memorizing certain portions of theevaluation or by intentionally underperforming in the preseason baselineassessment to which subsequent tests will be compared. It lacks validityand reliability of the data obtained.

The Balance Error Scoring System (BESS) is a static balance assessmentthat requires an individual to perform 3 stances on 2 different surfacesfor a total of 6 trials. Each trial is 20 seconds in duration, and thescore is equal to the cumulative number of balance errors. While balanceitself is a relatively objective measure of sensorimotor function,significant variability in scoring is reflected by poor interrater andeven intrarater reliability. An individual's score on the BESS can alsofluctuate during the course of an athletic season independent ofconcussion status, and the BESS score can be further confounded bylower-extremity injuries and/or fatigue.

The timed tandem gait test (TGT) is a dynamic assessment of sensorimotorfunction in which a participant is timed while walking heel-to-toe alonga 38-mm-wide piece of tape that is 3 m in length. Each assessmentconsists of 4 identical trials, and the best time among the 4 trials isrecorded as the official score. Timed TGT performance can be affected byexercise and lacks specificity for concussions and reliability.

The Sport Concussion Assessment Tool, 3rd Edition (SCAT-3) consists of acarefully selected series of tests, including a focused physical exam, a22-symptom checklist, the GCS, and cognitive and sensorimotorassessments. The SCAT-3 benefits from its ability to assess a range ofneurological functions, including orientation, cognition, memory,balance, and gait. However, the duration of the test battery isapproximately 15-20 minutes, which is not optimal in the setting oftime-limited athletic competition. Furthermore, the SCAT-3 is designedto be administered by medical practitioners, which limits its utility inyouth and high-school sports, in which medical professionals are notnecessarily available for sideline concussion screening. Similar to manyof the other concussion screening tools, the SCAT-3 also requiresbaseline testing for comparison, which carries additional logisticalchallenges. Finally, SCAT-3 is not 100% sensitive for identifyingathletes with concussion and is more of a complementary test rather thanthe primary stand-alone tool for concussion detection. The checklist'ssensitivity has been shown to have a significant degree of variability.A revised SCAT-5 incorporates cognitive and balance testing with 6 pagesof forms to complete and takes more than 10 minutes to complete. Thistest also cannot be used as stand-alone method to diagnose concussion.

The King-Devick Test (KDT) is a rapid mobile application of visualperformance measure. It takes about two minutes to complete and comparespre-test results. This is a rapid number-naming task requiring theathlete to read aloud 3 cards of irregularly spaced single-digit numbersas quickly as possible. Scoring is based on both speed and accuracy.This test does not measure eye movements such as vergence or otheroculomotor parameters, such as VOR or visual pursuit. This test alsocannot measure fine ocular movements such as saccades. At its core, theKDT is an assessment of visual function, but it also assesses theintegrity of attention. The KDT requires a baseline assessment forcomparison. In the setting of sideline concussion screening, the KDT isideal in that it takes less than 1-2 minutes to complete but is 80%-86%sensitive for detecting concussion and thus should not be used as astand-alone test and has testing reliability variability due to largelearning effect.

Brain Scope uses commercial smartphone hardware, using an Androidoperating system and a custom sensor to record and analyze a patient'selectroencephalogram (EEG) after head, injury. The test is based on atechnique called quantitative electroencephalography, or QEEG. QEEGrelies on computerized analysis of a set of changes that are distinctiveof a traumatic brain injury. It requires a baseline measurement becausewithout a baseline measurement it can't be known for sure whethersomeone's EEG signal is in fact abnormal. The difference could be otherthings besides concussion, like a medication, a previous head injury, orsomething else entirely. It also requires trained personnel forinterpretation and is not completely portable. It has not been wellaccepted, is more difficult to interpret and is more time consuming.

A blood test, called the Brain Trauma Indicator (BTI), helps determinewhether a CT scan is needed in people with suspected concussion. Thetest measures two brain-specific proteins, ubiquitin C-terminalhydrolase (UCH-L1) and glial fibrillary acidic protein (GFAP), that arerapidly released by the brain into the blood within 12 hours of seriousbrain injury. Test results can be available within three to four hours(or approximately 16 hours after the serious injury). Low blood levelsof these proteins indicate that, if the person has damage, it is likelytoo small to be seen on a CT scan. Obviously, this cannot be doneacutely, but has to be done in a medical facility, which may not bereadily available for remote injuries. Failure to provide informationimmediately, may also fail to prevent second events, as the athlete ormilitary personnel may have returned to play or previous activities.

ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing) is aneurocognitive assessment administered online in a controlledenvironment. ImPACT has two components: baseline testing and post-injurytesting, which are used in conjunction to determine if a patient cansafely return to an activity. ImPACT testing is a 25 to 30-minute onlinetest. ImPACT is designed for ages 12-59. Only licensed healthcareproviders can administer and interpret post-injury test_results and thisis not available in most cities. It therefore cannot test the individualacutely and reliability is poor.

Helmet Instrumented Telemetry (HITS), that measures the magnitude anddirection of an impact to a helmet is now used in some helmets, but donot appear to be reliable predictor of concussion or concussionseverity.

Prior Art Ocular Concussion Assessment Methods

The ability to track objects in the environment is an important featurefor humans to interact with their surroundings. In particular, theability to recognize the presence of an environmental hazard is directlylinked to our ability to fix our gaze on a visualized target ofinterest, recognize the threat, and implement a plan of action.Therefore, the central nervous system (CNS) is imposed with a series oftasks and time constraints that require a harmonic integration ofseveral neural centers located in multiple regions and linked through anefficient transmission of information. There are central nervous system(CNS) impairments in individuals with mTBIs long after the lasttraumatic episode. Even a mild TBI (mTBI), also known as a concussion,will result in oculomotor abnormalities and can cause visual problems,including, but not limited to dysfunction with visual fixation on avisual element or visual object of interest and vergence. In addition toglare and photophobia, individuals commonly report problems includingblurred vision; squinting; double vision/diplopia; difficulty reading;watching television; using computers; loss of visual acuity; colordiscrimination; brightness detection; contrast sensitivity; visual fielddefects; visuospatial attention deficits; slower response to visualcues; visual midline shift syndrome, affecting balance and posture;impaired accommodation and convergence; nystagmus; visual pursuitdisorders; deficits in the saccadic system; extraocular motilityproblems resulting in strabismus; reduction in stereopsis; readingproblems, including losing one's place, skipping lines, and slow readingspeed.

During periods of fixation, our eyes are never perfectly stable butdisplay small involuntary physiological eye movements. These take theform of disconjugate slow drifts) (1-3′/˜0.05°, small conjugatemicrosaccades (5-10′/˜0.17°, 1-2 per second) and disconjugate tremors(15″/0.004°; 30-80 Hz) superimposed on the slow drifts. A further classof involuntary physiological eye movement is called saccadic intrusions(SI). They are conjugate, horizontal saccadic movements which tend to be3-4 times larger than the physiological microsaccades and take the formof an initial fast eye movement away from the desired eye position,followed, after a variable duration, by either a return saccade or adrift. Saccadic intrusions are involuntary, conjugate movements whichtake the form of an initial fast movement away from the desired eyeposition and followed after a short duration, by either a returnsecondary saccade or a drift.

When analyzing eye movement accuracy, abnormal saccadic eye movementswhile performing smooth pursuit, diminished accuracy of primary saccadiceye movement, and a widespread slower reaction to visual stimuli can allbe seen. More commonly the most relevant saccadic parameters measuredare peak velocity, latency, and accuracy. Visually guided saccadic tasksshowed longer latencies and reduced accuracy irrespective of theseverity of TBI. There is also increased eye position error,variability, widespread delays in reaction times and significantadaptations to normal patterns of eye tracking movements. Saccadicintrusions (irregular episodic occurrences of fast eye movements) areclassified according to whether or not the intrusive saccades areseparated by a brief interval in which the eyes are stationary. Althoughsaccadic reaction times appear delayed in mild TBI, they can be seen toresume to normal levels one to three weeks after injury.

Saccadic intrusions, and saccadic oscillations are fixationinstabilities which impair vision, and usually are involuntary andrhythmic. Saccadic oscillations are caused by abnormalities in thesaccadic eye movement system. Abnormal saccades move the eyes away fromthe intended direction of gaze, and corrective saccades carry the eyesback. In saccadic intrusions, such as square-wave jerks andmacrosquare-wave jerks, brief pauses occur, or intersaccadic intervals,between the opposing saccades. In ocular flutter and opsoclonus, nointersaccadic intervals occur. Three of four types of SI monophasicsquare wave intrusions (MSWI), biphasic square wave intrusions (BSWI)and double saccadic pulses (DSP) have been noted to be exclusivelysaccadic, while the fourth type, the single saccadic pulses (SSP),exhibits a slow secondary component. Following mTBI the impaired abilityto generate predictive (or anticipatory saccades) can also be seen. Themajority of individuals have vergence system abnormalities (convergenceinsufficiency), which typically results in oculomotor symptoms relatedto reading.

Thus, the measurement of ocular performance or eye movement responsescan greatly enhance the ability to determine whether a traumatic braininjury has occurred. However, the currently available ocular performancetechnology is not optimized for concussion evaluation.

The EYE-SYNC System quantifies the predictive timing of dynamicvisuo-motor synchronization (DVS) between gaze and target duringpredictive circular visual tracking. Eye-Sync utilizes a head worngoggles which measures smooth pursuit, while the head remainsmotionless. The test takes 1 minute, while the user visualizes a dotmoving in a circle. Eye trackers measures spatial and timing variabilityand has 80% test reliability for detecting concussions. However, visualpursuit testing cannot test the vestibular system, which is alsointimately related to concussions. It therefore lacks more sophisticatedtesting, such as seen with vestibular ocular reflex testing. It is alsonot a stand-alone device, but requires an accessory computer attached.

The Eye-Guide Focus system features an eye-tracking headset and aportable chin mount. Its software runs on an iPad facing the user andthe user has to follow a small white circle moving across the screenwith their eyes in order to set the baseline of how their eyes normallyfunction. This system lacks complete portability and uses similartechnology to Eye-Sync.

Neuro Kinetics I-PAS System is a battery of tests using goggles andmeasures ocular motor, eye motor and reaction times to test whethercertain neural pathways have been altered or are behaving abnormally.I-Pass test subjects wear a pair of goggles linked to a laptop andallows the tester to measure infinitesimally small changes in thesubject's eye muscles while the test is taking place. The data generatedfrom the test, coupled with the clinical exam, allows the doctor to makea final diagnosis. (a non-portable device). This testing is performed ina clinical environment, lacks portability and multiple pieces ofequipment, with medical personnel, are required to interpret the dataobtained.

Oculogica's EyeBOX uses ocular motility to detect cranial nerve functionand provides a BOX Score indicative of the presence and severity ofbrain injury. The EyeBOX requires no pre-test calibration which can omitcritical information if the subject being evaluated has indeed suffereda TBI or concussion. This test requires the user to rest their chin andforehead comfortably on the device and watch a video for less than fourminutes. This requires laboratory testing and also lacks portability.

The evidence shows that more sophisticated testing is needed which ishighly specific for concussion detection, portable and can be used onthe field of play, in a military operative environment or in any otherenvironment where a concussion is likely to occur. Specifically,oculomotor parameter measurement as described with this invention usingocular and head sensing elements and transducers have shown highsensitivity and accuracy in identifying athletes who experienced asport-related concussion. When comparing all these tests, the VOR hasthe highest percentage for identifying the individual with concussions.

CONCLUDING SUMMARY

It is desired to provide a head impact measurement and mitigation systemand/or method that is fundamentally superior to the prior art indetermining whether a concussion has occurred and in reducing the chanceof one or more concussions that can lead to chronic traumaticencephalopathy.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading the followingdetailed description of non-limiting embodiments thereof, and onexamining the accompanying drawings, in which:

FIG. 1 shows a face guard that comprises an ocular performance measuringsystem;

FIG. 2 shows an ocular performance calibration test method;

FIG. 3 shows a static active ocular performance test method;

FIG. 4 shows a static passive ocular performance test method;

FIG. 5A shows a vestibulo-ocular gain measurement;

FIG. 5B shows a vestibulo-ocular phase measurement;

FIG. 5C shows ocular saccades;

FIG. 6A illustrates an example of the left eye gain of a healthyperson's vestibulo-ocular response to motion between 0.1 Hertz and 1.28Hertz;

FIG. 6B illustrates an example of the phase lead and lag for a healthhealthy person's vestibulo-ocular response to motion between 0.1 Hertzand 1.28 Hertz;

FIG. 6C illustrates an example of the asymmetry readings betweencounterclockwise and clockwise horizontal rotation of a healthy person'svestibulo-ocular response to motion between 0.1 Hertz and 1.28 Hertz;

FIG. 7A shows an unaltered visual element;

FIG. 7B shows the visual element of FIG. 7A that has been altered bydefocusing the visual element and superimposing a target;

FIG. 8 shows a scene that can be used for optokinetic testing;

FIG. 9 shows a scene that can be used for testing eye-trackingperformance;

FIG. 10 shows a scene that can be used for dynamic visual acuitytesting;

FIG. 11 shows a scene that can be used for scan path tracking;

FIG. 12 shows the relationship between target movement, eye position,eye velocity, and eye acceleration for smooth pursuit;

FIG. 13A shows the relationship between target movement, eye position,and eye velocity for a saccade;

FIG. 13B shows the typical relationship between saccade amplitude andsaccade duration; and

FIG. 14 shows a generalized method for ocular testing using a faceguardunit.

It should be understood that the drawings are not necessarily to scale.In certain instances, details that are not necessary for anunderstanding of the invention or that render other details difficult toperceive may have been omitted. It should be understood that theinvention is not necessarily limited to the particular embodimentsillustrated herein.

DETAILED DESCRIPTION

The ensuing description provides preferred exemplary embodiment(s) only,and is not intended to limit the scope, applicability or configurationof the disclosure. Rather, the ensuing description of the preferredexemplary embodiment(s) will provide those skilled in the art with anenabling description for implementing a preferred exemplary embodiment.It should be understood that various changes could be made in thefunction and arrangement of elements without departing from the spiritand scope as set forth in the appended claims.

Specific details are given in the following description to provide athorough understanding of the embodiments. However, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details.

In one embodiment, the present invention comprises head tracking andocular-based sensors integrated into a face guard. The ocular-basedsensors comprise at least one camera that views at least one eye of thefaceguard wearer. The camera is configured to measure an eye musclemovement response. The information from this eye camera can be combinedwith sensors that measure head rotation to determine whether humanperformance has been degraded by a blow to the head. The vestibularocular reflex, after an impact, is an example of one eye muscle movementresponse that could be measured using this embodiment. This vestibularocular reflex could be used to determine if the wearer has suffered aconcussion or mild traumatic brain injury. Other eye muscle movementresponses that could be detected can include, but are not limited topupillometry, ocular saccades, visual pursuit tracking, nystagmus,vergence, convergence, divergence, eye-lid closure, dynamic visualacuity, kinetic visual acuity, retinal image stability, foveal fixationstability, and focused position of the eyes or visual fixation at anygiven moment.

Eye muscles, also known as extraocular muscles, are located within theorbit but are extrinsic and separate from the eyeball itself. They actto control the movements of the eyeball and the superior eyelid. Thereare seven extraocular muscles: the levator palpebrae superioris,superior rectus, inferior rectus, medial rectus, lateral rectus,inferior oblique, and superior oblique. Functionally, these sevenextraocular muscles can be divided into two groups: (1) the recti andoblique muscles, which are responsible for eye movement; and (2) thelevator palpebrae superioris, which is responsible for superior eyelidmovement. Three antagonistic pairs of muscles control eye movement: thelateral and medial rectus muscles, the superior and inferior rectusmuscles, and the superior and inferior oblique muscles. These musclesare responsible for movement responses of the eye along three differentaxes: horizontal, either toward the nose (adduction) or away from thenose (abduction); vertical, either elevation or depression; andtorsional, movements that bring the top of the eye toward the nose(intorsion) or away from the nose (extorsion). Each extraocular musclehas specific action in order to maintain accurate visual fixation andtracking in response to a stimulus. For example, the lateral rectus,when contracting, responds by abducting the eyeball, the medical rectusmuscle contraction response is seen with adduction of the eyeball.Within the eyeball are intra-ocular muscles, the ciliary muscles (whichchanges the shape and power of the lens) and the (radially oriented)dilator pupillae and (circular) sphincter pupillae muscles, both whichregulate the pupillary size.

An eye muscle movement response can be either voluntary or involuntaryin response to attempting to acquire accurate visual fixation on astable or moving visual element(s) of interest or protect the eye. Eyetracking does not directly measure the actual muscle activity, itmeasures the visible movement response of the eyeball or features of theeye with voluntary or involuntary stimulus. Eye tracking can measure theeye muscle movement responses of the eye and/or eyelid by using visiblefeatures or visible reflections of the eye, such as from the pupil,iris, cornea, sclera or from the junctions or boundaries of theseregions. The principal types of movement include voluntary motion (bothvertical and horizontal), tracking (both voluntary and involuntary) andconvergence. Additionally, there are pupillary reactions and movementsto control the lens. Although the eyes can be moved voluntarily, mosteye movements are through reflexes. Specific extraocular and intraocularmuscles of the eye respond to visual, touch, auditory or head positionalstimuli in order to maintain fixation on stationary or moving visualelement(s) or protect the eye. An example of an eye muscle movementresponse is the vestibular ocular response. The vestibulo-ocular reflex(VOR) produces eye muscle movement in response to changes in headposition, while the eyes remain fixed on a visual target.

Definitions

The definitions that follow apply to the terminology used in describingthe content and embodiments in this disclosure and the related claims.

Alert filters are algorithmic computational tools that take in sensordata, compare that data against a set of rules and thresholds, andoutput a result that is typically in the form of a binary outcome. Therules and thresholds represent the sensitivity and reporting levelsdesired for the use case. A representative sample of this type of filteris a Random Forest Ensemble. The result can be robust in the data itcontains but should lead to a true/false response to each rule orthreshold.

An artificial intelligence system is a computer system that attempts toimplement aspects of human-level intelligence, in which a machine canlearn and form judgements to improve a recognition rate for informationas it is used. Artificial intelligence technologies include a machinelearning (deep learning) technology that uses an algorithm thatclassifies/learns the characteristics of input data by itself and anelemental technology that simulates functions such as recognition,judgment, like the human brain by utilizing a machine learningalgorithm. The elemental technology may include any one of thefollowing: a linguistic comprehension technique for recognizing humanlanguages/characters, a visual comprehension technique for recognizingobjects as in human vision, a reasoning/predicting technique for judgingand logically reasoning and predicting information, a knowledgeexpression technique for processing human experience information asknowledge data, and an operation control technique for controllingautonomous driving of the vehicle or the motion of a robot. A machinelearning classifier is a machine learning tool. A machine learningclassifier can be an algorithmic computer vision tool that takes aninput image data frame (a picture for example), processes thepixel-level information against a target, and outputs a result. Such aclassifier can attempt to identify a pattern within the pixels andcompare that pattern to a target pattern set. Classifiers can be of amachine learning type (representatives of this group includeconvolutional neural networks or general adversarial networks) or of astatic type (representatives of this group include Haar cascades andLocal Binary Patterns), but typically require some form of training foroptimization. In another embodiment of this faceguard technology,measurement of eye muscle movement responses, such as with the VOR in areaction to head movement changes, can be designed with an eye sensorconfigured for use with a machine learning classifier or computer visionlearning classifier, which can identify a pattern in response to aninput image frame from the video camera; and compare the pattern to atarget pattern set.

Biometrics are defined as physiological measurements and consist of theoutputs of sensors that measure the activity of a human body in responseto things that are experienced through our senses or imagined. This canbe direct measurement of the central nervous system (e.g., the brain) ororgans that are connected to the peripheral nervous system (e.g., thepupils of the eyes, sweat glands in our skin). The goal of biometricsgenerally is to measure bodily responses that are more direct indicatorsof emotional states. There are many possible biometrics, including DNA,odor, gait, height, handwriting, speech, and vision. Vision-basedbiometrics can use image sensors and algorithms derived from machinevision. Applications for biometrics include controlling access to abuilding (physical access), authenticating a user to allow access tosome resource (for example, accessing a secured Web site), andidentifying a person from among others.

Blinks are the involuntary act of shutting and opening the eyelids,elicited when the cornea is stimulated by touch, impending movementtoward the eye, bright light, loud sounds, or other peripheral stimuli.The purpose of these involuntary responses are to protect the eyes frompotentially harmful stimuli. They are known to reflect changes inattention and thus they are likely to reflect an individual's cognitiveeffort. In particular, fewer blinks have been associated with increasedattention. For example, a study shows that surgeons had a lower numberof blinks when performing surgery as compared to when they were engagedin casual conversations. In addition to the number of blinks, theduration of blinks can also indicate cognitive effort. For example,shorter blink durations were associated with increased visual workloadduring a traffic simulation task. Similarly, comparing blink data duringa hard (math problem solving) and easy task (listening to relaxingmusic), people exhibited shorter blink durations during the hard task.When the eyes are closed during a blink, there is no incoming visualinformation to process.

A concussion is defined as an immediate and transient loss ofconsciousness accompanied by a brief period of amnesia after a blow tothe head.

A convolutional neural network (CNN) is defined as an artificialintelligence/machine learning algorithm which can take in an inputimage, assign importance (learnable weights and biases) to variousaspects/objects in the image and be able to differentiate one from theother. The architecture of a CNN is analogous to that of theconnectivity pattern of neurons in the human brain and was inspired bythe organization of the visual cortex. Individual neurons respond tostimuli only in a restricted region of the visual field known as thereceptive field. A collection of such fields overlap to cover the entirevisual area.

The corneal reflex is defined as a blinking of both eyes in response totactile stimulation of the cornea.

An eye correcting algorithm (ECA) is an algorithmic computer visiontool. It builds upon a classifier by attempting to account for movementbetween the camera itself and the eye being observed. This movement istypically referred to as slippage and the ECA takes the input data frame(the same picture as the classifier), processes the information todetermine appropriate offsets, and supplies the offset parameters as itsoutput.

The dynamic visual acuity (DVA) can be used interchangeably with kineticvisual acuity (KVA) as they both have the same meaning. In thisdocument, DVA will be used to assess impairments in a person's abilityto perceive objects accurately while actively moving the head, or theability to track a moving object. It is an eye stabilization measurementwhile the head is in motion. In normal individuals, losses in visualacuity are minimized during head movements by the vestibulo-ocularsystem that maintains the direction of gaze on an external target bydriving the eyes in the opposite direction of the head movement. Whenthe vestibulo-ocular system is impaired, visual acuity degrades duringhead movements. The DVA is an impairment test that quantifies the impactof the vestibulo-ocular system pathology on a user's ability to maintainvisual acuity while moving. Information provided by the DVA iscomplementary to and not a substitute for physiological tests of the VORsystem. The DVA quantifies the combined influences of the underlyingvestibulo-ocular pathology and the person's adaptive response topathology. DVA testing is sometimes obtained for those persons suspectedof having an inner ear abnormality. Abnormalities usually correlate withoscillopsia (a visual disturbance in which objects in the visual fieldappear to oscillate or jump while walking or moving). Currently with DVAtesting, worsening of visual acuity by at least three lines on a visualacuity chart (e.g., Snellen chart or Rosenbaum card) during head turningfrom side to side at 1 Hz or more is reported as being abnormal. Innormal individuals, losses in visual acuity are minimized during headmovements by the vestibulo-ocular system that maintains the direction ofgaze on an external target by driving the eyes in the opposite directionof the head movement When the vestibular system is impaired, visualacuity degrades during head movements. Individuals with such ocularperformance deficits can improve their dynamic acuity by performingrapid “catch-up” saccadic eye movements and/or with predictive saccades.

Dynamic visual stability (DVS) and retinal image stability (RIS) can beused interchangeably. In this document, DVS will be used to describe theability to visualize objects accurately, with foveal fixation, whileactively moving the head. When the eye moves over the visual scene, theimage of the world moves about on the retina, yet the world or imageobserved is perceive as being stable. DVS enables a person to preventperceptual blurring when the body moves actively. The goal of oculomotorcompensation is not retinal image stabilization, but rather controlledretinal image motion adjusted to be optimal for visual processing overthe full range of natural motions of the body or with head movement.Although we perceive a stable visual world, the visual input to theretina is never stationary. Eye movements continually displace theretinal projection of the scene, even when we attempt to maintain steadyfixation. The human eye has the highest visual acuity in a smallcircular region of the retina called fovea, having the highest densityof cone photoreceptors. For this reason, the eyes are moved to directthe visual targets to the center of the fovea (behavior called scan pathof vision). The act of looking can roughly be divided into two mainevents: fixation and gaze shift. A fixation is the maintenance of thegaze in a spot, while gaze shifts correspond to eye movements. Ourvisual system actively perceives the world by pointing the fovea, thearea of the retina where resolution is best, towards a single part ofthe scene at a time. Using fixations and saccadic eye movements tosample the environment is an old strategy, in evolutionary terms, butthis strategy requires an elaborate system of visual processing tocreate the rich perceptual experience. One of the most basic feats ofthe visual system is to correctly discern whether movement on the retinais owing to real motion in the world or rather to self-movement(displacement of our eyes, head or body in space). The retinal image isnever particularly stable. This instability is owing to the frequentoccurrence of tremors, drifts, microsaccades, blinks and small movementsof the head. The perceptual cancellation of ocular drift appears toprimarily occur through retinal mechanisms, rather than extra-retinalmechanisms. Attention also plays a role in visual stability, mostprobably by limiting the number of items that are fully processed andremembered.

Eye tracking means the process of measuring where a subject is looking,also known as our point of gaze. In one embodiment, eye tracking can beperformed using a light source, such as near-infrared light, directedtowards the center of the eyes (pupil), causing detectable reflectionsin both the pupil and the cornea (the outer-most optical element of theeye). These resulting reflections, the vector between the cornea and thepupil, can be tracked by an infrared camera. This is the opticaltracking of corneal reflections, known as pupil center cornealreflection. These measurements are carried out by an eye tracker, asensor or sensing unit that records the position of the eyes and themovements they make.

Fixation is defined as a collection of relatively stable gaze pointsthat are near in both spatial and temporal proximity. During fixation,the eyes hold steady on an object, and thus fixation reflects attentionto a stimulus. A number of studies have associated fixation-relatedmetrics to cognitive effort and the number of fixations has been shownto strongly correlate with task performance. Because task performance isalso correlated with effort expenditure, this result suggests a linkbetween fixation frequency and cognitive effort. In a preferredembodiment, the faceguard technology as described herein can measurefixation metrics, including but not limited to point of fixation or gazepoint, duration of fixation, fixation count and intervals betweenfixations, which can be used to detect and monitor concussions, TBIs,cognition, cognitive deficits, alertness and fatigue.

Focused position of the eyes can be defined as the position ororientation of the eyes to provide a clear image of a visual element orvisual object/target of interest on the fovea.

Foveal Fixation Stability (FFS) refers to the ability to maintain animage on the fovea, which is crucial for the visual extraction ofspatial detail. If the target image moves 1° from foveal center, or ifrandom movement of the image on the fovea exceeds 2°/sec, visual acuitydegrades substantially. Either of these conditions may occur ifdeficiencies in oculomotor control compromise the ability to maintaintarget alignment within these limits. Many aspects of oculomotorfunction do change with age. For example, smooth pursuit movements slowwith age, and the range of voluntary eye movements becomes restricted,especially for upward gaze. Dynamic visual acuity (DVA), FFS, and thevestibulo-ocular reflex (VOR) decline with age.

The term gaze is synonymous with fixation. Gaze serves as a reliableindicator of attention and can reflect cognitive effort. Additionally,other major eye movement behaviors such as fixations, saccades, blinks,and pupillary responses can provide distinct information about cognitiveeffort in response to task demand.

Global shutter is defined as an imaging sensor that is capable ofsimultaneously scanning the entire area of an image. This is contrastedwith a rolling shutter where the image area is scanned sequentially,typically from the top to bottom. Some consumer and industrial machinevision and 3D sensing need a global shutter to avoid motion blur andapplications which can be incorporated in this technology include facialauthentication and eye tracking.

Kalman filtering (also known as Linear Quadratic Estimation (LQE)) is analgorithm that uses a series of measurements observed over time,containing statistical noise and other inaccuracies, and producesestimates of unknown variables that tend to be more accurate than thosebased on a single measurement alone, by estimating a joint probabilitydistribution over the variables for each timeframe.

Machine learning is defined as the science of getting computers to learnand act like humans in order to improve their learning over time in anautonomous fashion by feeding them data and information in the form ofobservations and real-world interactions. Machine Learning fundamentallyis the practice of using algorithms to parse data, learn from it, andthen make a determination or prediction about something in the world.This entails getting computers to act without being explicitlyprogrammed and is based on algorithms that can learn from data withoutrelying on rules-based programming. Embodiments entail the developmentof computer models for learning processes that provide solutions to theproblem of knowledge acquisition and enhance the performance ofdeveloped systems or as described by the adoption of computationalmethods for improving machine performance by detecting and describingconsistencies and patterns in training data. As an example, eventdetection can be challenging in eye movement data analysis. However, afully automated classification of raw gaze samples as belonging tofixations, saccades, or other oculomotor events can be achieved using amachine-learning approach. Any already manually or algorithmicallydetected events can be used to train a classifier to produce similarclassification of other data without the need for a user to setparameters. Machine-learning techniques can lead to superior detectioncompared to current state-of-the-art event detection algorithms and canreach the performance of manual coding. There are numerous algorithmsdesigned to solve a specific problem, such as smooth pursuit detection,noise resilience, separating the slow and fast phase in nystagmus,detecting microsaccades, online event detection, or removing saccadesfrom smooth pursuit data. Most of these algorithms work well within theassumptions they make of the data. Examples of common assumptions arethat the input must be high-quality data, or data recorded at highsampling frequencies, and there is no smooth pursuit in it. Allalgorithms come with overt settings that users must experiment with toachieve satisfactory event detection in their data set, or covertsettings that users have no access to. When the sampling frequency istoo low, or too high, or the precision of the data is poor, or there isdata loss, many of these algorithms fail. Other techniques, such aseye-movement event detectors that uses machine learning are available.Machine learning can choose feature combinations and select appropriatethresholds. In another embodiment of this system using video or imagecameras, machine learning can be used in conjunction with computervision to determine ocular parameters, including but not limited to VOR,pursuit tracking and pupillometry. In another embodiment of thefaceguard technology discussed herein, the sensor data acquired can beconfigured to be fused through a machine learning algorithm (i.e.alternatively known as a filter) to account for dynamic noise inherentin the sensors and fused sensor data from eye and head movement can moreaccurately measure and predict information transmitted to theinterface/communication unit where it can communicate to an externaldevice.

The near accommodative triad or near/accommodative response is athree-component reflex that assists in the redirection of gaze from adistant to a nearby object. It consists of a pupillary accommodationreflex, lens accommodation reflex, and convergence reflex.

Nystagmus is an abnormal involuntary or uncontrollable eye movementcharacterized by jumping (or back and forth) movement of the eyes, whichresults in reduced or limited vision. It is often called “dancing eyes”.Nystagmus can occur in three directions: (1) side-to-side movements(horizontal nystagmus), (2) up and down movements (vertical nystagmus),or (3) rotation of the eyes as seen when observing the front of the face(rotary or torsional nystagmus).

Ocular parameters are measurable factors that define and determine thecomponents, actions, processes, behavior and functional ability of theeye, eyeball and eyelid. Included in ocular parameters are measurementsand/or evaluations regarding the ocular reflexes, ocular saccades,pupillometry, pursuit tracking during visual pursuit, vergence, eyeclosure, focused position of the eyes, dynamic visual acuity, kineticvisual acuity, retinal image stability, foveal fixation stability, andnystagmus. Reflexes included in the measured ocular parameters includethe vestibular ocular reflex, pupillary light reflex, pupillary darkreflex, near accommodative triad, comeal reflex, palpebral oculogyricreflex (Bell's reflex) and the optokinetic reflex. Measuring movementsof eye includes the extraocular muscles (which move/rotate the eye), thelevator (which raises the eyelid), the ciliary muscles (which helps tofocus by changing the lens shape) and the pupillary muscle (whichdilates or constricts the pupil). The use of measuring eye musclemovement responses, with eye tracking, has been shown to havesignificant value in detecting, measuring and monitoring or managinghuman health conditions, including but not limited to: concussions,traumatic brain injury, vision impairment, neurologic disorders or theneurologic status, cognition, alertness, fatigue and the situationalawareness of humans. Additionally, these eye muscle movement responsescan provide methods for detecting, measuring, monitoring and managingphysiologic impairments due to alcohol and drugs because of their effecton the brain, brainstem, inner ear vestibular system and oculomotorresponses. Eye tracking sensors can measure horizontal eye movement,vertical eye movement, or rotation of a human eyeball. All thesemeasurements entail eye muscle movement responses. Commonly, horizontal,vertical, and torsional eye positions are expressed as rotation vectorsand eye muscle movements are described as rotations about threeprincipal axes. Horizontal rotation occurs about the vertical Z-axis,vertical rotation about the horizontal X-axis, and torsion about theline of sight or Y-axis. The amount of rotation about each of the threeprincipal axes that is needed to describe a certain direction of gazeand torsional orientation of the eye depends upon the order ofsequential rotations (e.g. horizontal, followed by vertical and thentorsional). Some oculomotor tasks, such as retinal image stabilization,utilize all three degrees of freedom whereas other tasks, such asvoluntary gaze shifts, only require two degrees of freedom, (i.e. gazedirection and eccentricity from primary position). Binocular alignmentof retinal images with corresponding retinal points places additionalconstraints on the oculomotor system. Because the two eyes view theworld from slightly different vantage points, the retinal imagelocations of points subtended by near objects differ slightly in the twoeyes. This disparity can be described with three degrees of freedom(horizontal, vertical, and torsional components) that are analogous tothe angular rotations of the eye. The eye rotates not only abouthorizontal and vertical axes but about its line of sight with the top ofthe eye moving either temporally (extorsion) or nasally (intorsion).Good alignment is a multi-stage process. Neural connectivity betweenmotor and premotor areas serving horizontal, vertical and torsional eyemovement serves as a substrate for coordinated movement for the eyeball.

Ocular reflexes are involuntary responses that are usually associatedwith protective or regulatory functions They require a receptor,afferent neuron, efferent neuron, and effector to achieve the desiredprotective or functional effect.

Optokinetic nystagmus: The optokinetic reflex, or optokinetic nystagmus,consists of two components that serve to stabilize images on the retina:a slow pursuit phase and a fast “reflex” or “refixation” phase. Thereflex is most often tested with an optokinetic drum or projected visualimage with alternating stripes of varying spatial frequencies.

Palpebral oculogyric reflex (or Bell's reflex) is an upward and lateraldeviation of the eyes during eyelid closure against resistance, and itis particularly prominent in patients with lower motor neuron facialparalysis and lagophthalmos (i.e. incomplete eyelid closure).

The pupillary light reflex is an autonomic reflex that constricts thepupil in response to light, thereby adjusting the amount of light thatreaches the retina. Pupillary constriction occurs via innervation of theiris sphincter muscle, which is controlled by the parasympatheticsystem.

The pupillary dark reflex is an autonomic reflex that dilates the pupilin response to dark. It can also occur due to a generalized sympatheticresponse to physical stimuli and can be enhanced by psychosensorystimuli, such as by a sudden noise or by pinching the back of the neck,or a passive return of the pupil to its relaxed state.

Pupillometry refers to an objective way of measuring pupil size, andmore specifically, the diameter of the pupil. Often pupil parameters aremeasured including: maximum, minimum and final pupil diameter, latency,amplitude and peak and average constriction and dilation velocitiesunder numerous stimulus conditions including: dim pulse, dim step,bright pulse, bright step, bright red step and bright blue step. It hasbeen observed that concussions and mild traumatic brain injury adverselyaffects the pupillary light reflex suggesting an impairment of theautonomic nervous system. Quantitative pupillary dynamics can also serveas an objective mild traumatic brain injury biomarker and thesepupillary measurements can be reliably replicated. Quantitativepupillometry can be a measure of concussion analysis and associated withintracranial pressure. Changes in pupil size, which are controlled bythe involuntary nervous system, can serve as a reliable proxy of mentaleffort. For example, when people are asked to memorize numbers, retainthem in memory, or perform multiplication, the size of their pupil seemsto correlate with the difficulty of the task. Similarly, variation inpupil size can also carry information about cognitive effort. Forexample, the level of difficulty measured as the number of stepsrequired to complete a task has been shown to impact pupil dilationvariation. Increased cognitive load measured as implicit and explicittime limit also has a significant impact on pupil dilation variation.Eye tracking studies provide ample evidence that certain eye movementbehaviors (i.e., fixations, saccades, blinks, and pupillary responses)have the potential to reveal information about cognitive effort. Thereare a number of machine learning studies that have successfully used eyemovement data to predict a variety of different behaviors. Saccades andblinks are associated with cognitive effort, but also show that themetrics related to saccades and blinks were among most effectivevariables for detecting task demand. While fixation serves as a reliableand direct indicator of attention and thus information processing, moreeffective in classifying task demand appears to be the saccade and blinkeye movement behaviors, which take place between, and not during,fixations. Eye movement data carries distinct information about taskdemand. In some studies, pupillary responses were more effective thanother eye moment behaviors in detecting task demand. In particular,saccade-to-fixation pupil dilation and pupil variation ratios proved tobe most valuable in detecting task demand. In another embodiment, thefaceguard technology discussed herein can measure eye movementbehaviors, including but not limited to fixations with and without headmovement, saccades, eyeblinks and pupillary responses to detect andmonitor the neurologic status, concussion, cognition, alertness andfatigue.

A saccade is a rapid movement of an eye between visual fixation points.Saccades are quick, simultaneous movements of both eyes in the samedirection. They range in amplitude from the small movements made whilereading, for example, to the much larger movements made while gazingaround a room. We cannot consciously control the speed of movementduring each saccade; the eyes move as fast as they can. One reason forthe saccadic movement of the human eye is that the central part of theretina (known as the fovea) plays a critical role in resolving objects.By moving the eye so that small parts of a scene can be sensed withgreater resolution, body resources can be used more efficiently.

Saccadic eye movements are said to be ballistic because the saccadegenerating system cannot respond to subsequent changes in the positionof the target during the course of the eye movement. If the target movesagain during this time, the saccade will miss the target, and a secondsaccade must be made to correct the error. While visual information isnot processed during saccadic eye movements, they still can provideinformation about viewing behavior. According to the theory of visualhierarchy a stimulus is inspected by scanning it through a sequence ofvisual entry points. Each entry point acts like an anchor, which allowsthe user to scan for information around it. According to thisperspective, longer duration of saccadic eye movements could indicateincreased cognitive effort in finding a suitable entry point into avisual display. The saccade that occurs at the end of a head turn withsomeone who has an abnormal VOR is usually a very clear saccade, and itis referred to as an overt saccade. An overt saccade is indicative ofabnormal semicircular canal function on the side to which the head wasrotated. For example, an overt saccade after a leftwards head rotationmeans the left semicircular canal has a deficit. Covert saccades aresmall corrective saccades that occur during the head movement of aperson with abnormal inner ear function. Covert saccades reduce the needfor overt saccades that occur at the end of the head movement and aremore difficult to identify than overt saccades. Covert saccades are veryfast. This makes them almost impossible to detect by the naked eye, andtherefore sensitive eye tracking measurements are required to detectcovert saccades. There is a rapid deceleration phase as the direction ofsight lands on the new target location. Following a very short delay,large saccades are frequently accompanied by at least one smallercorrective saccade to further approach a target location. Correctivesaccades can occur even if the target has been made to disappear,further supporting the projected, ballistic nature of saccadicmovements. However, corrective saccades are more frequent if the targetremains visible.

Saccade accuracy, amplitude, latency and velocity can be measured withoculomotor eye movements, most commonly with saccades, vergence, smoothpursuit, and vestibulo-ocular movements. Saccades can be elicitedvoluntarily, but occur reflexively whenever the eyes are open, even whenfixated on a target. They serve as a mechanism for fixation, rapid eyemovement, and the fast phase of optokinetic nystagmus. The rapid eyemovements that occur during an important phase of sleep are alsosaccades. After the onset of a target appearance for a saccade, it takesabout 200 milliseconds for eye movement to begin. During this delay, theposition of the target with respect to the fovea is computed (that is,how far the eye has to move), and the difference between the initial andintended position is converted into a motor command that activates theextraocular muscles to move the eyes the correct distance in theappropriate direction. The latency, amplitude, accuracy and velocity ofeach respective corrective saccade and latency totals and accuracy canbe calculated.

Saccade accuracy refers to the eye's ability to quickly move andaccurately shift from one target fixation to another. Saccade adaptationis a process for maintaining saccade accuracy based on evaluating theaccuracy of past saccades and appropriately correcting the motorcommands for subsequent saccades. An adaptive process is required tomaintain saccade accuracy because saccades have too short a durationrelative to the long delays in the visual pathways to be corrected whilein flight.

Saccade amplitude refers to the size of the eye movement response,usually measured in degrees or minutes of arc. The amplitude determinesthe saccade accuracy. This is sometimes denoted using “gain”. It is alsodescribed as the angular distance the eye travels during the movement.For amplitudes up to 15 degrees or 20 degrees, the velocity of a saccadelinearly depends on the amplitude (the so-called saccadic mainsequence). Saccade duration depends on saccade amplitude. In saccadeslarger than 60 degrees, the peak velocity remains constant at themaximum velocity attainable by the eye. In addition to the kind ofsaccades described above, the human eye is in a constant state ofvibration, oscillating back and forth at a rate of about 60 Hz.

Saccade velocity is the speed measurement during the eye movement. Highpeak velocities and the main sequence relationship can also be used todistinguish micro-saccades from other eye movements, such as oculartremor, ocular drift and smooth pursuit.

Saccade latency is the time taken from the appearance of a target to thebeginning of an eye movement in response to that target. Disorders oflatency (timing) can be seen with saccades, VOR and visual pursuit.

Saccadic Inhibition. Studies of eye movements in continuous tasks, suchas reading, have shown that a task-irrelevant visual transient (forexample a flash of a portion of the computer display) can interfere withthe production of scanning saccades. There is an absence or near-absenceof saccades initiated around 80-120 ms following the transient. Thisinhibitory effect (termed saccadic inhibition (SI)) is also observed insimple saccade experiments using small visual targets and it has beensuggested that SI may be like or underlie a remote distractor effect.

Sensor Fusion is an algorithm that combines sensory data or data derivedfrom disparate sources such that the resulting information has lessuncertainty than would be possible when these sources were usedindividually. The term ‘uncertainty reduction’ in this case can meanmore accurate, more complete, or more dependable, or refers to theresult of an emerging view, such as stereoscopic vision (calculation ofdepth information by combining two-dimensional images from two camerasat slightly different viewpoints). The sensors can be of the same type(such as cameras for a stereoscopic image) or of differing types (suchas combining accelerometer and gyroscopic data in a Kalman Filter). Theycan also be complementary (independent sensors measuring differentproperties combined to give a more complete view), competitive(independent sensors measuring the same property for fault tolerance orredundancy), or cooperative (using multiple sensor measures to deriveinformation not available to any single sensor). In an embodiment of thefaceguard described herein, the head tracking sensor and eye sensor canbe configured to use such a sensor fusion algorithm to provide moreaccurate information regarding measurement of eye fixation with headmovement. Alternatively, different eye sensors measuring eye features atdifferent points can be configured for sensor fusion to obtain moreaccurate data regarding the eye muscle movement responses.

Situational awareness (SA) is defined as being aware of one'ssurroundings, comprehending the present situation, the context, meaning,the possible progression of events and being able to predict outcomes.It is a cognitive process that involves perceiving and comprehendingcritical elements of information during a certain task. It is simply‘having an idea of what's going on around you. It is a key human skillthat, when properly applied, is associated with reducing errors of humanperformance activities. Eye-tracking sensors, which measure ocularmovements (e.g. eye and eyelid) can be used to provide an objective andqualitative measure of the initial perception component of SA. There isevidence that eye tracking can improve learning and aid feedback of useractivity.

Slippage is defined as movement of the faceguard relative to thewearer's head. Slippage typically causes faceguard movement that is outof phase with the wearer's head. The slippage offset is an algorithmthat accounts for slippage and computes an appropriate value that can beused to synchronize sensor data. In another embodiment, the faceguard isconfigured for measuring and correcting slippage offsets. Themeasurement and correction of slippage offsets is carried out by one ormore sensors selected from the group of: the existing multi-axisinertial measurement unit (IMU), the existing imaging sensor, anadditional IMU, and a wider field of view image sensor.

Smooth pursuit movements are slow tracking movements of the eyesdesigned to keep a moving stimulus on the fovea. Such movements areunder voluntary control in the sense that the observer can choosewhether or not to track a moving stimulus.

Vergence is the simultaneous movement of both eyes in oppositedirections to rapidly obtain or maintain single binocular vision orocular fusion, or singleness, of the object of interest. It is oftenreferred to as convergence or divergence of the eyes, to focus onobjects that are closer or further away from the individual. In order tomaintain binocular vision, the eyes must rotate around a vertical axisso that the projection of the image is in the center of the retina inboth eyes. Vergence measurements can easily be performed. Normally,changing the focus of the eyes to look at an object at a differentdistance will automatically cause vergence and accommodation, known asthe accommodation-convergence reflex. Convergence is the simultaneousinward movement of both eyes toward each other, usually to maintainsingle binocular vision when viewing an object. Vergence tracking occursin the horizontal, vertical, and/or cyclorotary dimensions. Vergencerequires that the occipital lobes be intact, and the pathway involvesthe rostral midbrain reticular formation (adjacent to the oculomotornuclei) where there are neurons that are active during vergenceactivities. It comprises a complex and finely tuned interactiveoculomotor response to a range of sensory and perceptual stimuli. Thereis an important interaction between the vergence system and vestibular(inner ear balance) system. To keep the eyes focused on a visual elementor object of interest, while the head is moving, the vestibular systemsenses head rotation and linear acceleration, and activates the eyes tocounterrotate to keep gaze constant even though the head is moving. Asan example, this is what enables us to see a tennis ball while movingour head. The problem becomes more difficult at near vision, because theeyes are not located at the center of rotation of the head, but ratherare about 10 cm anterior to the axis of rotation. Therefore, when aperson is focused on a near target (such as 10 cm away), the amount ofeye movement needed to keep the target fixated is much greater than theamount needed to view a similar object 100 cm away. This additional eyemovement is supplied by the otoliths (linear acceleration sensingelement) that produce eye movement that are roughly inverselyproportional to the distance of the target from the center of the eye.Persons with disorders of their otoliths, might reasonably have aselective problem with stabilizing their vision while the head ismoving, at near vision. Vergence can be also be adversely affected byother factors including aging, visual abnormalities, concussion andtraumatic brain injury (TBI).

Vergence eye movements are used to track objects that move in depth inone's binocular visual field to attain and maintain a fused and singlepercept. When we shift our gaze from a far object to a near object, oureyes converge, the lenses of our eyes modify their focus (accommodate),and our pupils often constrict. These three combined responses aretermed the near triad. Convergence is the simultaneous inward movementof both eyes toward each other, usually in an effort to maintain singlebinocular vision when viewing an object. This is the only eye movementthat is not conjugate, but instead adducts the eye. Divergence is thesimultaneous outward movement of both eyes away from each other, usuallyin an effort to maintain single binocular vision when viewing an object.It is also a type of vergence eye movement. The mechanism and control ofvergence eye movements involves complex neurological processes that maybe compromised in individuals with traumatic brain injury, thusfrequently resulting in a wide range of vergence dysfunctions andrelated near-work symptoms, such as oculomotor-based reading problems.It has been determined that 90 percent of individuals having mTBI haveoculomotor dysfunction encompassing vergence, accommodation, version,strabismus, and cranial nerve palsy and report vision-based symptoms.Following mTBI, a vergence system abnormality is often the most commondysfunction. Vergence movements align the fovea of each eye with targetslocated at different distances from the observer. Unlike other types ofeye movements in which the two eyes move in the same direction(conjugate eye movements), vergence movements are disconjugate (ordisjunctive). They involve either a convergence or a divergence of thelines of sight of each eye to see an object that is nearer or fartheraway. Convergence is one of the three reflexive visual responseselicited by interest in a near object. Other components of the so-callednear reflex triad are accommodation of the lens, which brings an objectinto focus, and pupillary constriction, which increases the depth offield and sharpens the image on the retina.

Visual pursuit means the movement of the eyes in response to visualsignals. Smooth pursuit eye movements allow the eyes to closely follow amoving object. It is one of two ways that humans and other visualanimals can voluntarily shift gaze, the other being saccadic eyemovements. Pursuit differs from the VOR, which only occurs duringmovements of the head and serves to stabilize gaze on a stationaryobject. Most people are unable to initiate pursuit without a movingvisual signal. The pursuit of targets moving with velocities of greaterthan 30°/s tend to require catch-up saccades. Most humans and primatestend to be better at horizontal than vertical smooth pursuit, as definedby their ability to pursue smoothly without making catch-up saccades.Most humans are also better at downward than upward pursuit. Pursuit ismodified by ongoing visual feedback. Smooth pursuit is traditionallytested by having the person follow an object moved across their fullrange of horizontal and vertical eye movements.

Visual pursuit tracking can be defined as measuring a person's eyemovement ability to match a visual element or visual target of interestmovement. Visual pursuit eye movements utilize some of thevestibulo-ocular reflex pathways and require a visual input to theoccipital cortex to permit locking of the eyes onto a visual element,visual object or target of interest. Pursuit movements are described tobe voluntary, smooth, continuous, conjugate eye movements with velocityand trajectory determined by the moving visual target. By tracking themovement of the visual target, the eyes maintain a focused image of thetarget on the fovea. A visual stimulus (the moving visual target) isrequired to initiate this eye movement. Pursuit gain, which is the ratioof eye velocity to target velocity, is affected by target velocity,acceleration and frequency. Visual pursuit tracking may be related tofactors that are difficult to quantify, such as the degree of alertnesspresent in persons, visual acuity or the visibility of the pursuittarget. Visual pursuit tracking can be decayed with alcohol, centrallyacting medications such as anticonvulsants, minor tranquilizers,preparations used for sleep. It is also clear that visual pursuitperformance declines with age and can be adversely affected byvestibular dysfunction, central nervous system disorders and trauma,such as concussions and traumatic brain injury (TBI).

Visual pursuit accuracy is defined by the ability of the eyes to closelyfollow a moving object. The pursuit of targets moving with velocities ofgreater than 30°/s tends to require catch-up saccades. Smooth pursuitaccuracy represents how closely the percentage of time the smoothpursuit velocity value remains within the target velocity value.

Visual pursuit movements are much slower tracking movements of the eyesdesigned to keep the moving stimulus on the fovea. Such movements areunder voluntary control in the sense that the observer can choosewhether to track a moving stimulus. Although it may appear that our eyesare not moving when we fixate an object, in fact they are in continualsmall-scale motion, showing irregular drift and tremor, interspersed byminiature saccadic movements (less than 0.5 degrees). These fixationaleye movements are essential to prevent our visual percept from fading.Pursuit consists of two phases—initiation and maintenance. Measures ofinitiation parameters can reveal information about the visual motionprocessing that is necessary for pursuit.

Visual pursuit acceleration—this is the rate of change of the eyevelocity. The first approximately 20 milliseconds of pursuit tends to bethe same regardless of target parameters. However, for the next 80milliseconds or so, target speed and position have a large effect onacceleration.

Visual pursuit velocity—After pursuit initiation, speed of the eyemovement (velocity) usually rises to a peak and then either declinesslightly or oscillates around the target velocity. This peak velocitycan be used to derive a value for gain (peak velocity/target velocity).It is usually near the velocity of the target. Instead of using peakvelocity, it is also sometimes of interest to use measures of velocityat times relative to either target appearance or pursuit initiation. Eyevelocity up to 100 milliseconds after target appearance can be used as ameasure of prediction or anticipation. Velocity measured 100milliseconds after pursuit begins reveals something about the ability ofpursuit system in the absence of visual feedback.

Visual pursuit latency is defined by the time from target appearance tothe beginning of pursuit. The difficulty is defining when pursuitbegins. Usually it is measured from traces of eye velocity. It is oftencalculated by finding the intersection between two regression functionsone fitted to velocity about the time of target appearance, and thesecond fitted over the initial part of the pursuit response.

Vestibulo-ocular movements are defined as movements that stabilize theeyes relative to the external world, thus compensating for headmovements. These reflex responses prevent visual images from “slipping”on the surface of the retina as head position varies. The action ofvestibulo-ocular movements can be appreciated by fixating an object andmoving the head from side to side; the eyes automatically compensate forthe head movement by moving the same distance but in the oppositedirection, thus keeping the image of the object at more or less the sameplace on the retina. The vestibular system detects brief, transientchanges in head position and produces rapid corrective eye movements.Sensory information from the semicircular canals directs the eyes tomove in a direction opposite to the head movement. While the vestibularsystem operates effectively to counteract rapid movements of the head,it is relatively insensitive to slow movements or to persistent rotationof the head. For example, if the vestibulo-ocular reflex is tested withcontinuous rotation and without visual cues about the movement of theimage (i.e., with eyes closed or in the dark), the compensatory eyemovements cease after only about 30 seconds of rotation. However, if thesame test is performed with visual cues, eye movements persist. Thecompensatory eye movements in this case are due to the activation of thesmooth pursuit system, which relies not on vestibular information but onvisual cues indicating motion of the visual field.

The vestibulo-ocular reflex is defined as a reflex, initiated by headmovement which activates the vestibular system of the inner ear andresults in eye movement. This reflex functions to stabilize images onthe retinas (when gaze is held steady on a visual target) during headmovement by producing eye movements in the direction opposite to headmovement, thus preserving the image on the center of the visual field.The vestibulo-ocular reflex (VOR) entails eye movements in the oppositedirection of head movement, in order to maintain steady gaze and preventretinal image slip. Motion signals from the utricle, saccule, and/orsemicircular canals in the inner ear travel through the utricular,saccular, and/or ampullary nerves to areas in the vestibular nucleus,which sends output to cranial nerve III, IV, and VI nuclei to innervatethe corresponding extraocular muscles. Horizontal VOR involvescoordination of the abducens and oculomotor nuclei via the mediallongitudinal fasciculus. An abnormal VOR will involve catch-up saccadeswhile the patient rotates his or her head, and it can indicatebilateral, complete, or severe (>90%) loss of vestibular function. VORcan be assessed in several ways. During the Doll's eye maneuver, theindividual continuously fixates on an object while the examiner moveshis or her head from side to side, and the examiner watches theindividual's eyes for catch-up saccades. VOR can also be assessed byproviding a visually displayed target upon which an individual isfocused up and multiple eye and head movement measurements are taken asthe individual's head is rotated. Comparisons are made between the headand eye measurements. In normal circumstances, as the head rotates tothe right 30 degrees corresponding eye movements occur in the oppositedirection 30 degrees to maintain eye fixation on the target. One canexpect approximately a 10 msec difference between head movement and eyemovement. A delay of eye movement response greater than 20-30 msec wouldindicate a VOR abnormality. Caloric stimulation can also be used toexamine the VOR. Irrigation of the external auditory meatus with icewater causes convection currents of the vestibular endolymph thatdisplace the cupula in the semicircular canal, resulting in a fastcomponent of eye movement toward the opposite ear.

Basic Science: Concussion and Traumatic Brain Injury (TBI)

Broadly speaking, a concussion, the most common type of traumatic braininjury, results from impact or impulsive forces to the head, neck orface and typically affects the central nervous system and the peripheralvestibular system. Most concussions meet criteria for mild traumaticbrain injury. Mild traumatic brain injury (mTBI) has been defined asloss of consciousness less than 30 minutes and less than 24 hours and noskull fracture. A moderate TBI has a loss of consciousness greater than30 minutes and less than 24 hours, with or without skull fracture.Severe TBI is characterized by loss of consciousness greater than 24hours, with contusion, hematoma or skull fracture.

Due to the variability and subtlety of symptoms, concussions may gounrecognized or be ignored, especially with the pressure placed onathletes to return to competition. There is public consensus thatundiagnosed, and therefore untreated, concussions represent asignificant long-term health risk to players.

Closed head injury can cause several different types of brain injuryincluding coup, contre-coup, acceleration-deceleration trauma,rotational trauma and molecular commotion. Acceleration-decelerationtrauma causes discrete lesions which affect only certain areas of thebrain. Both rotational trauma and molecular commotion cause diffusedamage that impairs many aspects of brain function.Acceleration-deceleration trauma occurs when the head is accelerated andthen stopped suddenly, as with players colliding, which can causediscrete, focal lesions to two areas of the brain. The brain will suffercontusions at the point of direct impact and at the site directlyopposite the point of impact, due to the oscillation movement of thebrain within the skull (e.g. coup or site of contact and contrecoup oropposite site of contact respectively). Trauma results from theoscillation (movement) of the brain against bony projections on theinside of the skull. Brain injuries may also occur as a result ofacceleration-deceleration trauma unaccompanied by impact. The prefrontalareas and the anterior portion of the temporal lobes are the parts ofthe brain most often affected by acceleration-deceleration trauma. Thus,if the brain is repeatedly propelled against the front part of theskull, there is likely to be major injuries. Rotational trauma occurswhen impact causes the brain to move within the cranium at a differentvelocity than the skull. This results in a shearing of axons within theupper spinal cord, brainstem and midbrain. Because this type of injurydamages neural connections rather than gray matter, it can affect a widearray of cerebral functions and should therefore be considered a type ofdiffuse injury. Molecular commotion is a disruption in the molecularstructure of the brain which may cause permanent changes in both whiteand gray matter. This type of diffuse brain injury may occur in theabsence of discrete lesions.

The major effects of trauma on the brain can be divided into twocategories: primary and secondary (or late) effects. The primary effectsare those that are caused directly by the head trauma and includeconcussion, contusion, and laceration of the central nervous system.

Concussion is a reversible state of diffuse cerebral dysfunctionassociated with a transient alteration in consciousness. Most oftenthere is a brief period of loss of consciousness. However, athletes maybe only severely stunned or dazed. Typically, there is loss of memoryfor recent events (retrograde amnesia), and this may extend for someseconds or minutes following the injury and, rarely, with more severeimpact, for days or more. A variable period of inability to learn newmaterial (anterograde amnesia) typically follows recovery ofconsciousness and may be dense enough to leave the individual with nomemory of early post injury occurrences. Rarely, some players are unableto remember ongoing occurrences. The retrograde amnesia is presumed tobe caused by a mechanical distortion of neurons, probably in thetemporal lobes, which consolidate the memory trace. The anterogradeamnesia is presumed to be the result of distortion of the mesialtemporal-limbic circuits known to be necessary for learning.

The underlying pathophysiology of concussion appears to be a shearingeffect. Rapid displacement of the head, in either acceleration ordeceleration injury, causes a swirling of the cerebrum within thecranium, and shearing forces play most markedly at the junctions betweenbrain tissues of different density and location. Rotational injuries maybe particularly damaging, since the brainstem torques while there is alot of inertia against the rotation of the cerebral cortex. This resultsin torsion of the nerve fibers in the core of the brain (i.e., thereticular activating system). Another major zone of diffuse axonalinjury is the interface between gray and white matter. It is here and inthe core of the rostral brainstem that microscopic evidence of rupturedaxons can be found pathologically. It is not surprising that theathlete's resistance to future concussion tends to decline with repeatedconcussions or that repeated concussion may lead to dementia.

Contusions of the brain are bruises usually associated with more severetrauma than necessary for concussion. They are most prominent at thesummits of gyri, the cerebral poles (particularly the frontal poles andthe anterior temporal lobe), and portions of the brainstem. All theseregions lie close to the bony and dural surfaces of the cranial cavity.They may directly underlie the site of the violent blow to the craniumor may be opposite the site of impact (contrecoup). The contusions canusually be seen acutely on CT or MRI scans.

Laceration of the brain usually follows cranial trauma severe enough tocause fracture of the skull and penetrating injury to the brain by skullfragments or foreign objects. However, fracture of the skull need not beassociated with laceration or contusion or major concussion. On theother hand, laceration may on occasion occur with severe shearing forcesunassociated with fracture. Usually some form of hemorrhage(intracerebral, subdural, epidural) is associated with laceration.

The secondary effects of cranial trauma that may further compromisebrain function are edema, hypoxia, hemorrhage, infection and epilepsy.Edema may be the result of diffuse shearing of capillary, glial, andneuronal membranes or may be secondary to local contusion or laceration.Edema can generate local pressure that can compromise both arterial andvenous cerebral blood flow, causing ischemia and more edema. This mayprecipitate a vicious cycle sometimes impossible to reverse. The masseffect of edema, focal or diffuse, can cause rostrocaudal brainstemdeterioration (possibly with herniation), a major cause of delayed deathfrom head trauma. Increased intracranial pressure (ICP), mostly due toedema but added to by any intracranial bleeding, is a major cause ofsecondary injury. High pressure decreases the perfusion pressure inbrain blood vessels (since the perfusion pressure is the mean arterialpressure minus the intracranial pressure). If this is too low, therewill be further damage to neural tissue due to ischemia, which willresult in further edema and an even greater increase in pressure.

Intracranial hemorrhage, arterial or venous, intra- or extracerebral, isa frequent sequela of cranial trauma and may be great enough to causerostrocaudal deterioration of neural function and death if notrecognized and attended to immediately. Rostrocaudal deterioration, ifrapid, may itself cause hemorrhage by downward stretching and tearing ofthe paramedian penetrating arteries of the midbrain and pons. Subduraland epidural hematomas both can be treated via surgical intervention,which can be curative if undertaken prior to irreversible brain damage.Both epidural and subdural hematoma are extracerebral. For this reason,and because they are soft masses, there tends to be relatively littleeffect on the underlying and compressed cerebral hemispheres. However,due to distortion of the brain itself, secondary rostrocaudal distortionof the brainstem is the process that usually gives rise to the majorclinical signs: depression of consciousness (reticular formation),hemiparesis (cerebral peduncles), eye signs (third and sixth nerves),and respiratory pattern abnormalities.

Herniation, the process of squeezing brain tissue from one intracranialcompartment into another, is often the terminal occurrence since thisproduces permanent damage in the region of herniation.

Epidural hematomas are most often arterial. They are usually the resultof transection of the middle meningeal artery by a skull fracture thatpasses through the middle meningeal groove. It must be emphasized,however, that fracture is not necessary since the skull has elasticitythat may permit the violent blow to rupture the artery which is pinnedbetween the dura matter and the skull. Because of the location of themiddle meningeal artery, the clots typically lie over the lateralhemisphere (temporal and/or parietal lobes). Since the epidural hematomais under arterial pressure, it typically continues to grow unlessevacuated. However, because the dura is adhered to the inside of theskull, and since the clot is between these layers, the growth of theclot is over hours. The typical middle meningeal artery epiduralhematoma is associated with a syndrome that appears within hours of theinjury.

Classically, trauma is associated with a concussive loss ofconsciousness. The athlete may awaken from this to achieve a good levelof consciousness (lucid interval) only to lose consciousness again frombrainstem distortion caused by the clot growth. If the bleeding is verysevere there is no lucid interval. The individual does not have time toawaken from the concussion before compressive brainstem deteriorationbegins. Surgical evacuation is critical. Less often, epiduralcollections may be the results of tears in the venous sinuses or leakagefrom the diploic veins. These hemorrhages may occur over any portion ofthe hemispheres or in the posterior fossa and are much slower.

A subarachnoid hemorrhage (SAH) involves bleeding into the space betweenthe surface of the brain (the pia mater) and the arachnoid, (e.g.between two of three coverings of the brain). Strengthening rod-likefibers known as fibrous trabeculae cross through the subarachnoid spaceto connect the arachnoid membrane to the pia mater, and cerebrospinalfluid fills the cavity to flow around the brain. The subarachnoid spacealso contains the blood vessels which supply the brain and spinal cordwith blood and oxygen. This cavity helps to cushion the brain to protectit from injury and continues down the spinal column along with thearachnoid membrane. The hemorrhage is presumed to arise from angularforces that cause shearing of vessels as acceleration/decelerationmovement of the brain occurs with linear/tangential/rotational injuries.The bridging veins tend to shear where they enter the dura after passingthrough the thin subdural space between the dura and arachnoid. Symptomsassociated with traumatic subarachnoid hemorrhage may or may notresemble those associated with spontaneous hemorrhage, as trauma caninvolve multiple injuries with overlapping symptoms. Because the bloodis under very low pressure (being from veins) the hematoma tends tocollect slowly, causing signs and symptoms that develop over days tomonths. Head trauma that can be so minor that it is not remembered mayresult in a subdural hematoma under these circumstances. Acute subduralhematomas are seen less frequently. They are usually associated withhead trauma severe enough to cause skull fracture and cerebral contusionor laceration. Epidural hematoma and intracerebral hematoma arefrequently associated. The mortality is extremely high, and the residualdysfunction of survivors is severe.

Arterial dissection may affect the carotid or vertebral arteries. Thisis usually associated with a tear in the intimal lining of the arteryand an accumulation of blood in the media. Stroke may result fromblockage of the artery or its branches or from artery-to-artery emboliarising from the site of vessel damage. The weakened artery may alsorupture (often into the subarachnoid space) with potentiallycatastrophic results.

Pathologic Findings in the Brain with Trauma

Impact forces may cause linear, rotational, or angular movements of thebrain, and more commonly a combination of these movements. In rotationalmovement, the head turns around its center of gravity, and in angularmovement it turns on an axis not through its center of gravity. Theamount of rotational force is thought to be the major component inconcussion and its severity. As the angular acceleration increases, therisk of mild traumatic brain injury increases respectively.

The parts of the brain most affected by rotational forces are themidbrain and diencephalon. It is thought that the forces from the injurydisrupt the normal cellular activities in the reticular activatingsystem located in these areas, and that this disruption produces theloss of consciousness often seen in concussion. Other areas of the brainthat may be affected include the upper part of the brainstem, thefornix, the corpus callosum, the temporal lobe, and the frontal lobe.Severe centrifugal forces exert tremendous shearing pressures on thebrainstem and upper spinal cord. A form of neurodegeneration reported inprofessional football players is “Chronic Traumatic Encephalopathy”(CTE). In addition to football players, CTE has been reported in otherathletes involved in violent blows to the head, in traumatic militaryactivities and in a few non-athletes with a history of TBI.

The syndrome of CTE begins insidiously, usually many years after theindividuals have stopped playing sports or their other activities, withinattention, mood and behavior disturbances, confusion, and memory loss,and progresses inexorably over many years to a stage of full-blowndementia and parkinsonism. The brain, in CTE, shows atrophy, dilatationof the lateral and third ventricles, and thinning of the corpuscallosum. Microscopic examination reveals hyperphosphorylated tau(p-tau) deposition in neurons, astrocytes, and cell processes aroundsmall vessels. These changes are patchy and affect the deeper parts ofcerebral sulci. Other neurodegenerative pathologies, including betaamyloid deposition in the form of diffuse or neuritic plaques, amyloidangiopathy, TDP-43-inclusions may co-exist with p-tau deposition. Taudeposition is the key cellular change in CTE. The cause of CTE isthought to be TBI, especially repeated cerebral concussions andsub-concussive trauma. In the acute phase, concussion, especiallyfollowing side-to-side hits to the head, causes diffuse axonal injury(DAI) and triggers the release of tau and beta amyloid in the brain.This, along with cerebral hypoxia, excitotoxicity and inflammatorymediators, set in motion a progressive destructive cascade that causesneurodegeneration many years later.

Diffuse axonal injury (DAI) is a special traumatic lesion, which occursfollowing blows to the unsupported head. During such injuries, thecerebrum goes into a back and forth gliding motion, pivoting around thebrainstem. The brainstem, together with the cerebellum, is held firmlyfixed by the tentorium, and the falx prevents side-to-side motion. Axonsare stretched but do not snap from this injury. Their sudden deformationcauses changes in the axonal cytoskeleton (compaction of neurofilaments,fracture of microtubules) that lead to an arrest of the fast axoplasmicflow. Components of this flow, including mitochondria and otherorganelles, accumulate proximal to the lesion and cause axonal swellings(spheroids). Some axons with mild lesions probably recover but manyeventually rupture. It takes several hours from trauma to axonalrupture. Influx of calcium through the stretched axolemma probablyinitiates the process that leads to the formation of spheroids.Mitochondrial dysfunction and neuroinflammation contribute to the localtissue injury. Ruptured axons undergo Wallerian degeneration leading toloss of neurological function. Loss of axons may lead to dying back ofneurons. Thus, DAI is a multifaceted process that evolves over time. Theswellings are located at nodes of Ranvier where the axolemma is moreliable to deform because there is no myelin. Brain damage is most severealong midline structures (corpus callosum, brainstem) where the shearforces are greatest, and at the cortex-white matter junction because ofthe change in the consistency of brain tissue. Cerebral concussion isthought to be a mild form of DAI without permanent pathology. The lossof consciousness in concussion is probably due to a functionaldisturbance of the reticular activating substance of the brainstem. Thisis part of the central nervous system that is subjected to the highesttwisting force during sagittal rotation of the hemispheres.

In one embodiment, the faceguard is configured to protect the face andcranial structures from the sequalae mentioned above and the system isconfigured to be a portable system for measuring, monitoring andmanaging the human health conditions resulting fromconcussions/traumatic brain injuries, including but not limited to suchas changes in the neurologic status, behavior and deficits in cognition,alertness, fatigue, and vision.

Faceguard as an Ocular Performance-Based Measurement Device

Referring now to the figures that describe the faceguard as a devicewhich can be used for ocular performance measurements, FIG. 1 shows thehead orientation sensor 404, is, FIG. 1 shows the head orientationsensor 404, is rigidly attached to the centered ocular performancemeasuring faceguard 440. In at least one embodiment, the headorientation sensor 404, senses (is responsive to) pitch, roll, and/oryaw. Pitch can be described as upward or downward movement of the face.Roll can be described as rotation of the face when viewed from thefront. Yaw can be described as leftward and rightward movement of theface when viewed from the front. The head orientation sensor 404, can beconstructed from one or more elements or it can be monolithic. The headorientation sensor 404, can use one or more accelerometers, gyroscopes,magnetometers, or any other relative or absolute position, velocity, oracceleration sensing device capable of being understood by anyoneskilled in the art. In one embodiment, the orientation sensor comprisesa micro-electro-mechanical system (MEMS) integrated circuit.

Placement of the user facing eye sensor on the faceguard elements iscritical, depending on the ocular parameter being measured. In oneembodiment, the eye sensor or imaging sensor can be attached to thefaceguard, vertically in line with the pupil and horizontally below thelevel of the infraorbital rim, to provide an unobstructed view when theuser is looking straight ahead. In this instance, accurate measurementrequires the sensor(s) to be located at an angle below the inferiormargin of the upper eyelid, where there is an unencumbered view of theeyeball characteristics. Measurements above the inferior margin of theupper eyelid would be adversely affected by the upper eyelid andeyelashes. The sensor can also be in another location which allows forvalid measurement of rotation of the human eyeball movement and visionor eyelid muscle movement and the test selected for measurement. Asanother example, eyelid muscle movement responses, can be measured bysensors located above the inferior margin of the upper eyelid. Acombination of eye sensors, attached to the faceguard, can be configuredto measure the movement characteristics of the extraocular eye musclemovement responses as well as intraocular eye muscle movement responses.The responses measured can detect not only evidence of a concussion andtraumatic brain injury, but also characteristics of alertness, fatigue,cognition and attention.

Eye sensors can also obtain biometric information.

Further referring to FIG. 1, the user facing eye sensor 406, is morespecifically an eye tracking digital video camera that is pointed at theeyes of the person. The eye sensor 406, can be responsive to any eyeposition, including vertical movement of the eyes (which representspitch), rotation of the eyes (which represents roll), and horizontalmovement of eyes (which represents yaw). It can also be responsive toeyelid position and eyelid movement. There can be one eye sensor camera406 that monitors only one eye, one eye sensor camera 406 with a wideangle that can monitor both eyes or two cameras with one to monitor eacheye. There can also be multiple cameras, to monitor different areas ofeach eye (e.g. eye response sensors tracking pupil features and cornealreflection surfaces). The eye sensor video camera 406, can be positionedanywhere around the eye, and can utilize visible or invisible light. Inone embodiment, the system shown at 440 further comprises anillumination source 530 to help illuminate the eyes of the person. Thisillumination source 530 could project infrared light, near infraredlight, or visible light in the direction of the person's eyes to helpimprove the sensitivity of the eye sensor 406 and make it less sensitiveof other light sources, which may produce noise and/or glint.

FIG. 1 illustrates one example of a faceguard-based ocular performancemeasuring system 440. In this embodiment, the faceguard frame is shownat 442. The faceguard frame 442 could comprise a plurality of rigidstructural members with at least one aperture for facilitating humanvision through the faceguard. The faceguard frame 442, could comprisematerials such as metal, carbon fiber, plastics, glass fiber, or anycombination of these materials or others capable of being understood byanyone skilled in the art. The faceguard frame 442, could comprise eyesensing elements and/or transducers for detecting and measuring eyemovements and a head orientation sensing element/transducer andcircuitry to the electronic elements such as:

-   -   the head orientation sensor shown at 404, connected to the        orientation sensor signal processor 412;    -   the eye-tracking digital video camera 406, connected to the eye        camera video processor 414; and    -   the central processing unit 418, memory unit 420, and        interface/communication unit 422 for communicating with an        external device 424.

The faceguard-based system 440, of FIG. 1 could have other sensors thatinterface with the electronic module 410. As an example, thefaceguard-based system 440, of FIG. 1 might have a forward-facing camera408, that communicates with a forward-facing camera interface 428, inthe electronic module 410. The forward-facing camera 408, can beresponsive to the eye sensors to measure the ocular performance. In thiscase, the central processing unit 418, or the external device 424, couldcombine the information from the head orientation sensors 404, theeye-tracking digital video camera 406, and the forward-facing camera408, to determine one of the ocular performance parameters describedherein.

Further referring to FIG. 1, the faceguard-based system 440, could alsohave a forward-pointing visual cue projector, shown at 430. This visualcue projector 430, could comprise a light source, and that light sourcecould comprise a light emitting diode (LED) or a laser. The light sourcecan project a cue 434 (visual object or visual element) onto a surface432. The surface 432 could be any available surface, examples of whichmight be an area of open or cleared ground nearby, or a subdued solidwall surrounding the field, positioned approximately 3 meters or 10 feetfrom the user. The user's ability to maintain his/her gaze on thisprojected cue 434 (visual object or visual element) on the surface 432can be used for calibration or testing of the ocular parameter beingmeasured. For example, the projected visual cue 434 could remainstationary when the user's head moves. The system could also beconfigured so that the visual cue 434 moves on the surface 432 and theuser's ability to follow this movement is measured. The visual cueprojector 430 could be controlled through a cue projector interface,shown at 436, that is part of the electronic module 410. The visual cueprojector 430 could be responsive to the central processing unit 418.

In humans, the horizontal semicircular canal and the utricle both lie ina plane that is slightly tilted anterodorsally (30 degrees) relative tothe nasal-occipital plane. When a person walks or runs, the head isnormally declined (pitched downward) by approximately 30 degrees, sothat the line of sight is directed a few meters in front of the feet.This orientation causes the plane of the horizontal canal and utricle tobe parallel with the earth and perpendicular to gravity. When the headis tilted downward 30 degrees and doing horizontal testing, the lateralsemicircular canals are maximally stimulated. Hence looking downwardseveral meters ahead at a surface is desired for testing. Therefore, itis desirable to have the cue projector 430 configured to project thevisual cue 434, several meters in front of the user, at an angleapproximately 30 degrees downward anterodorsally.

In another embodiment sensors can be attached to the faceguard formeasuring the characteristics of an impact. These sensors can be locatedin preferred positions most likely to detect linear and tangentialimpacts, relative to the rotational center of the wearer's head. As anexample, sensors used to measure linear impacts can be placed in thefrontal area and tangential impacts can be placed in the lateral ortemporal location.

Embodiments of the present invention could be implemented with eyetrackers (also described herein as eye sensors), shown for example at406 in FIG. 1, which are not video cameras. Examples of non-video cameraeye trackers can include electromyography trackers and electromagnetictrackers. In another embodiment, the eye sensor, 406, is an image sensorcapturing single images or frames from the sensor greater than 90 framesper second.

The faceguard-based system 440, of FIG. 1 could have other sensors thatinterface with the electronic module 410. The faceguard-based system440, could have an attached display and display interface. However, adisplay might be difficult for the person to use when active andtherefore could be removable and used only when testing is performed. Inan alternative embodiment, the faceguard system 440 of FIG. 1 couldcomprise a detachable drop-down display (not shown) in addition to thehead orientation sensor 404, and an eye tracking video camera, 414. Thedrop-down display unit could be attached to the faceguard to providevisible images for ocular performance testing as described herein. Inanother embodiment, the detachable drop-down display (not shown) couldperform multiple functions including: (a) providing the visual elementsrequired for measuring the ocular parameters; (b) a head orientationsensor; and (c) an eye tracking video camera, all located within thedrop-down display unit. This drop-down display unit could be a smartphone. This drop-down display unit would have its own power source andcould be configured for being responsive to other sensors, such as theforward-facing camera and/or impact sensors.

FIG. 2 shows an example of a vestibulo-ocular performance calibrationtest that can be implemented using a head-worn, or helmet affixed,faceguard unit. This test comprises the following configuration andsteps:

-   -   Establishing a faceguard unit 602 that comprises a        forward-facing visual cue projector (such as 430 in FIG. 1), a        head orientation sensor 606, and an eye tracking video camera        608 and a visual cue (434 in FIG. 1), from the visual cue        projector 430, in the background or a visual element in the        natural scene on the surface (432 in FIG. 1), which the user can        focus upon.    -   Head: In this test, the subject is asked to keep his/her head        motionless or the head is constrained to keep it motionless. The        head orientation sensor 606, is used to verify that the head is        stationary.    -   Eyes: The subject is asked to track a visual cue 434, in the        foreground or natural scene, by moving his/her eyes. The eye        sensor (typically a video camera) measures the subject's eye        movement 642, as visual elements are displayed.    -   Cue on Surface: The background area on the surface 432 behind        the projected visual cue 434, is subdued, plain, solid, and/or        non-distracting. In this test, the background can be similar to        the background that has been used in prior art VOR testing in        which the subject is asked to look at a plain background while a        bright white circular dot (the cue 434) projected on surface        432. In another embodiment of this test, cue 434 could be        visually enhanced for better image or target eye fixation. The        cue 434 can then behave in the following way:        -   1. The cue 434 is initially projected to be viewed centrally            610.        -   2. It is then projected to be viewed off center on a first            side (left or right) from the center of the user's gaze, as            shown at 612. This is typically about 20-25 degrees off            center.        -   3. It is then projected to be viewed off center on an            opposite (or second) side of the user's gaze, as shown at            614. This is also typically about 20-25 degrees off center.        -   4. This process of projecting the cue 434 on one side and            then on the opposite side is repeated as many times as            needed, as shown at 616.        -   5. This test can be conducted in the vertical, as well as            the horizontal direction.    -   Processor: The processor in the faceguard system then compares        eye movement to timing and appearance/disappearance and location        of the cue 434 to determine vestibulo-ocular performance 644.        Performance could be measured as accuracy, gain, phase,        symmetry, velocity, saccades, and/or visual acuity.

FIG. 3 shows an example of static active vestibulo-ocular performancetesting that can be implemented in a faceguard unit. This test comprisesthe following configuration and steps:

-   -   Establishing a faceguard unit 602 that comprises forward-facing        visual cue projector (such as 430 in FIG. 1), a head orientation        sensor 606, and an eye tracking video camera 608.    -   Display: In this test, the cue (434 in FIG. 1) is static—neither        the surface (432 in FIG. 1) nor the cue 434 moves or changes in        any way. The surface 432 comprises a subdued background and the        cue 434 is a projected centered white circular dot, similar to        what was described with reference to the test shown in FIG. 2.    -   Head: In this test, the subject is asked to actively move        his/her head each time he/she is given a prompt. The head should        typically move about 20-25 degrees off center about a vertical        axis (i.e. left or right). The head orientation sensor measures        changes in head pitch, roll, and/or yaw 640.    -   Eyes: The subject is instructed to keep his/her eyes focused on        the target visual element as the head moves. The eye sensor        (typically a video camera) measures eye movement 642, relative        to head movement 640.    -   Prompts are provided to tell the subject when to move the head.        These prompts can be audio prompts. The prompts could be haptic        (i.e. vibration on the side of the person's head). The prompts        could be visual (i.e. change of color or intensity of the visual        target element of interest). The prompts are typically timed        randomly so the subject doesn't try to anticipate the timing.

The test sequence is as follows:

-   -   1. The subject is instructed to move the head about 20-25        degrees in one direction when a first prompt is given, and to        hold the head in this new position 622.    -   2. The subject is instructed to move the head back about 20-25        degrees when the second prompt is given 624.    -   3. The subject is instructed to move the head in the first        direction a second time when the third prompt is given.    -   4. The process is repeated as many times as needed 626.    -   5. This test can be conducted in the vertical, as well as the        horizontal direction.    -   Processor: The processor in the faceguard system then compares        head and eye movement to timing and location and/or        appearance/disappearance of cues 434, and the location of these        visual elements to determine vestibulo-ocular performance 644.        Performance could be measured as accuracy, gain, phase,        symmetry, velocity, saccades, and/or dynamic visual acuity.

FIG. 4 shows a static passive vestibulo-ocular performance test that canbe implemented with a faceguard unit. This test comprises the followingconfiguration and steps:

-   -   Establishing a faceguard unit 602 that that comprises        forward-facing visual cue projector (such as 430 in FIG. 1), a        head orientation sensor 606, and an eye tracking video camera        608.    -   Display: In this test, the cue (434 in FIG. 1) seen is the same        as for the test described with reference to FIG. 2 and FIG. 3,        with a target visual element presented in the center 610.    -   Head: In this test, the assistant holds the subject's head and        moves it about 20-25 degrees each time 632. The head orientation        sensor measures changes in head pitch, roll, and/or yaw 640.    -   Eyes: The subject is instructed to keep his/her eyes focused on        the cue 434 as the head moves. The eye sensor (typically a video        camera) measures eye movement 642 relative to head movement 640.

The test sequence is as follows:

-   -   1. The assistant moves the subject's head about 20-25 degrees in        one direction and then holds it in this new position 632.    -   2. The assistant then moves the head back in the opposite        direction, 20-25 degrees and holds it 634.    -   3. The assistant moves the head in the first direction a second        time.    -   4. The process is repeated as many times as needed 636.

5. This test can be conducted in the vertical, as well as the horizontaldirection.

-   -   Processor: The processor in the faceguard system then compares        head movement and eye movement to determine vestibulo-ocular        performance 644. Performance could be measured as accuracy,        gain, phase, symmetry, velocity, saccades, and/or dynamic visual        acuity.

There can be many additional embodiments of the ocular performance testsdescribed with reference to FIG. 2, FIG. 3, and FIG. 4. Some of theseembodiments can include combinations of the variations listed here:

-   -   a. The cue (434 in FIG. 1) can be any other shape, size, or        coloring or have any other features capable of being understood        by anyone skilled in the art. Examples of these variations in        the target visual element could include:        -   A different shape (such as a shape comprising a cross hair);        -   Different contrast, either more or less;        -   Different intensity;        -   Different size;        -   Different focus, either more in-focus or out of focus;        -   Having one or more features in the visual element that move            relative to the rest of the visual element;        -   Different depths;        -   The appearance of a natural object (such as a baseball, a            basketball, or a bird); and/or;        -   Any combination of any of the above.    -   b. The test shown in FIG. 3 and/or FIG. 4 could be run with the        cue (434 in FIG. 1) not being stationary. This would make the        overall test more similar to a natural environment in which the        head, the eyes, and the visual world are all moving relative to        one another and relative to a stationary reference frame at all        times. The cue 434 could:        -   Move with the head movement;        -   Move contrary to the head movement;        -   Move perpendicular to head movement; and/or        -   Move in any random pattern not associated with head movement    -   c. The surface (432 in FIG. 1) (traditionally subdued, plain,        solid, and/or non-distracting), visualized through the face        guard, projected by the cue projector (430 in FIG. 1) or seen        through a display mounted to the faceguard unit, could be        presented any surface 432 understood by anyone skilled in the        art. Examples of variations of the surface 432 can include        embodiments in which the background is more natural and similar        to actual scene and/or any of the variations in the following        list:        -   The surface 432 can be completely static;        -   The presentation of the cue 434 on the surface 432 can have            moving and/or flashing elements;        -   The presentation of the cue 434 on the surface 432 can be            enhanced with auditory distractions consistent with the            imagery being displayed;        -   The presentation of the cue 434 on the surface 432 can be in            or out of focus;        -   The presentation of the cue 434 on the surface 432 can be            low intensity/contrast or high intensity/contrast relative            to the target of interest;    -   d. The face guard system can be responsive to a human generated        input signal including an auditory human input signal or a        haptic human input signal. The faceguard can be configured to        have an alerting signal for the user to turn the head or begin        the testing. This signal can occur randomly and therefore        resemble the static passive testing described previously,        without the need for an assistant.

Visual acuity, visual fixation ability, DVA (dynamic visual acuity), KVS(kinetic visual acuity), FFS (foveal fixation stability), and/or RIS(retinal image stability) can be tested using a system and methodsimilar to the vestibulo-ocular performance (VOP) test shown in FIG. 3and/or FIG. 4. The following are the main steps of a DVA, FVS, FFS orRIS test performed in this way using a faceguard:

-   -   Step 1. Perform a routine vision test by presenting a Snellen        chart, or something similar, using the display of the faceguard        unit. This is needed to establish a baseline visual acuity in a        static environment. This static test does not necessarily need        to be done with a Snellen chart (the standard chart used by        optometrists and ophthalmologists), it could also be done by        asking the subject to identify characters of various sizes,        positions, and/or locations.    -   Step 2. The subject is presented a cue (434 in FIG. 1), such as        a number or letter, in the visual field center in a manner        similar to step 610 of FIG. 3, but in the case of a DVA or FVS        test, the target visual element also comprises a character that        the subject must identify.    -   Step 3. The presentation of the cue 434 in the center of view on        the surface 432 changes at random times while the subject is        performing the steps described at 622, 624, and 626 in FIGS. 3        and/or 632, 634 and 636 in FIG. 4.    -   Step 4. The subject speaks out the character observed each time        it changes.

A faceguard system can also be used for positional testing. The subjectcould be asked to turn the head left, right, lie supine, while supinehead turns right, head turns left, then turn the body (roll) right andturn the body (roll) left. During each positional change, the eyes aretracked using the faceguard system to look for abnormal eye movements.If a visual cue (such as 434 in FIG. 1) was visible during this testing,the nystagmus would be suppressed. Visual elements in this instanceshould not have defining characteristics that might enable eye fixation.

A subject can be tested for BPPV using the method shown in FIG. 4 withthe assistant moving the head in a specific pattern that allows theindividual semicircular canals to be tested. Note that this means thehead is not moved the 20 degrees side-to-side, but is instead movedbased on standard protocol for the specific semicircular canal beingtested.

FIG. 5A, FIG. 5B, and FIG. 5C provide graphs of time versus angularvelocity that show how ocular response to a vestibular input can bemeasured. In these figures, the input is a rotation of the head, whichis shown as the solid line at 701. This head rotation information wouldtypically be measured using the head orientation sensor 404, that hasbeen shown in FIG. 1. The output is the eye response to the headrotation, which is shown as the dotted line at 702, 703, and 704, andwould typically be measured using the eye sensor, which is typically aneye tracking digital video camera 406, such as that shown in FIG. 1. Theactual eye response is in the direction opposite of the head rotation,701, but it has been plotted in the same direction to make it easier tocompare the input and output of a person's vestibulo-ocular system. InFIG. 5A, the velocity of the eyes is slower than that of the head, whichresults in a gain of less than 1.0 (i.e. a loss of amplitude 702). InFIG. 5B there is a delay between the rotation of the head and therotation of the eyes, which results in a phase lag, 703. In FIG. 5C, theeye rotation also lags the head rotation as shown at 704, but is caughtup by saccades 705, near the end of the rotation.

The measures shown in FIG. 5A, FIG. 5B, and FIG. 5C, can be plotted atdifferent frequencies and compared between the left eye and the righteye to create the plots shown in FIG. 6A, FIG. 6B, and FIG. 6C, whichillustrate some typical eye responses to oscillation of a healthyperson's head (e.g. vestibulo-ocular responses) in a horizontal plane atfrequencies ranging from 0.1 Hertz (1 cycle every 10 seconds) to 1.28Hertz (approximately 5 cycles every 4 seconds). More specifically, FIG.6A shows the gain at these frequencies, FIG. 6B shows the phase lead andlag at these frequencies, and FIG. 6C shows the relative symmetry (orasymmetry) between clockwise and counterclockwise oscillations. Itshould be noted that 0.1 Hertz to 1.28 Hertz is typical for the range offrequencies being used by prior art VOR testing systems. The embodimentsdescribed in this disclosure can include any frequency in the range of0.01 Hertz (1 cycle every 100 seconds) to 15 Hertz (approximately 15cycles every second).

FIG. 7A, FIG. 7B, FIG. 8, FIG. 9, FIG. 10, and FIG. 11 relate to targetsor visual elements that could be visualized or projected to facilitatemeasurement and/or improve ocular performance parameters such asvestibulo-ocular reflex function, visual pursuit, vergence, DVA, orother ocular parameters discussed herein. These targets or visualelements can be designed to enhance the eye fixation on the displayedimage when the head is motionless and the visual element is in motion.These targets or visual elements could also be designed for when thehead is in motion and the visual element is motionless or when both thehead and the visual element are in motion. In embodiments of theinvention, the visualized or projected targets or visual elements can bestatic in a position or location or the displayed targets or visualelements can be dynamically changing in position, depending on thespecific test being performed or rehabilitation method being used. Thetargets or visual elements, upon which the eyes are attempting to focus,can be of a variety of colors, sizes, shapes, and forms. They can changein color, size, shape, and form. They can contrast with other itemsbeing displayed to be more or less dominant in order to provide visualweight to enable fixation. These targets or visual elements can usespecific colors with more saturation and can change in scale andproportion, all in an effort to draw the fovea toward a specific pointof fixation on the target or visual element. Generally, it is importantto have some small point of focus on the visual element to lessen themicrosaccades and enhance the fixation ability. These same targets orvisual elements can be used for any oculomotor or ocular performancetesting including VOR re-training when a VOR abnormality exists.

The ideas expressed in the previous paragraph can best be explained bylooking at some examples. FIG. 7A shows an example of a target or visualelement in the form of a soccer ball 902. This soccer ball could be partof an existing scene viewed through a faceguard, or it could be an imageprojected from a light source attached to the faceguard, or projected ona display, attached to a faceguard. The soccer ball could be spinning,which might make the pattern on the ball distracting. FIG. 7B shows thevisual element (soccer ball) of FIG. 7A that has been altered bydefocusing the ball 904 and superimposing a target in the form of acrosshair 906, that is more precise for the eyes to focus on. It wouldbe more accurate fixation for the eyes to focus on the center of thecross-hair element shown in FIG. 7B than the element shown in FIG. 7Adue to the shape, size, contrast, and suppression of the pattern on theball. Although this example has been done using a black and white image,color and color contrast can be more effective. For example, the visualelement seen through the faceguard or with an attached faceguarddisplay, could be a red colored ball. Within the center of the red ball,a yellow circle can be present with a small black dot located in thecenter. This strongly contrasted central focal point could help the eyefocus on a specific point and lessen the “eye scanning” while undergoingany ocular performance measurement such as VOR testing or VORre-training. In another example, the element being viewed can be in theshape of a familiar object, such as a basketball, football, helmet orobject used in one's occupation. It can also have a centered focalpoint, created by high contrast and high color saturation compared tothe surrounding background to maintain the foveal fixation durationattractiveness and lessen microsaccades.

FIG. 8 shows a scene that can be used for optokinetic testing. Intraditional optokinetic testing, a person's head is motionless whileseated inside a moving drum with alternating black and white verticallines or alternatively, a hand-held drum, with alternating black andwhite vertical lines, is placed in front of the person. The drum isslowly rotated. The alternating lines induce nystagmus and causevisually induced motion sickness. The movement of the eyes is measuredas the drum rotates left and then right. Measurements can be atdifferent drum speeds. This same test can be performed using a faceguardby creating a visual image that includes elements that work just likethe vertical lines in the drum. Examples of natural scenes that aresimilar to the drum with lines can include examples such as being seatedin a car and watching a train go by or driving and watching thetelephone poles move by, such as the scene 910 shown in FIG. 8.Similarly, flying objects can be visualized as moving across the visualfield or along another plane of motion beside the person. These visualelements can also change in size, color or other dimensions, as theperson gets closer to the object or further from the visual element.Motion can occur in any direction or depth relative to the person, asthe eye movement is being assessed and measured.

FIG. 9, FIG. 10, and FIG. 11 illustrate other visual scenes, which canbe seen through the faceguard, or projected from a light source attachedto the faceguard, or used with a display attached to a faceguard. Thesevisual scenes can be used for ocular performance testing such as VOR,DVA, visual pursuit, and/or fixation ability testing. These scenes caninclude a test environment comprising natural background featurescombined with a visual element or target whose shape, color, size,motion, depth, or other attributes have been selected or added tofacilitate testing of vestibulo-ocular performance. FIG. 9 shows anexample of a scene which illustrates what this type of ocularperformance testing, such as with visual pursuit, DVA and/or VOR mightlook like. In the example shown in FIG. 9, the static scene can be atennis court and the moving target is the tennis ball 920. The visualelement (e.g. tennis ball) can remain motionless in the center,surrounded by a static court with 2 players on each side. The individualbeing tested would rotate his/her head in the horizontal and verticalplane while focusing on the visual element. Alternatively, as the personfocuses on the static visual element in front of the player on one sideof the court, it can suddenly become dimmed and re-appear on the otherside of the court. The individual being tested is required to rotate thehead each time the visual element reappears. This action can occur in aback and forth manner until the measurement is complete. For morecomplex testing, the surrounding courtside scene can be filled with fanswho are in motion. As another example, if the VOR is being tested on abasketball player, the dynamic background features may be a basketballcourt surrounded by fans, who are yelling and moving and the visualelement (e.g. basketball) may suddenly appear in the hands of a playeron one side, then dimmed or removed, and then alternatively appear inthe hands of another player on the other side, requiring the individualbeing tested to move the head in a horizontal manner. DVA measurementcan also be performed with dynamic changes of the target or visualelement of interest, requiring the person to identify characteristics ofthe element while it is in motion and the person is in motion andcomparing this to the SVA prior to the onset of the DVA test. FIG. 10shows letters that could be superimposed onto the moving element (suchas the tennis ball in FIG. 9) to test DVA. The target visual element 920in FIGS. 9, 930 and 932 in FIG. 10, or 940 in FIG. 11 could move indifferent trajectories, in different depths, the letters could be ofdifferent sizes, and the ball could move at different speeds andaccelerations to provide a meaningful test as shown by comparing visualelement 930 with visual element 932. The targets can be static orrapidly moving is a specific plane or scan path for (such as watching atennis ball move across the court or with tracking tests that have arotating target visual element) depending on the ocular parameter beingtested.

DVA testing could be performed with lettered optotypes and as the headrotates back and forth, the letters can rotate in position.Alternatively, numbers can be used as well as other familiar images ofobjects. The images can also be native or natural to the backgroundenvironment. As the head rotates back and forth, the target or visualelement is more difficult to visualize. If there is a VOR abnormality,for example the eyes will not be able to focus on the target or visualelement of interest and will subsequently have less fixation and moreerrors in identifying a visual element. Measurement can also beperformed with the visual element stationary and the head in motion orboth the visual element and head in motion, which would be morerealistic with everyday experiences. Static visual testing (SVT) can beperformed to obtain a normal visual test. The visual acuity can beobtained, while the head and the visual element, or optotype being seenthrough the faceguard or from a projected light 604, or with the use ofan attached display, are both motionless. Similar to a standard eyeexam, a faceguard system as described herein can measure a person'sstatic visual acuity (SVA), a component of DVA testing, by asking aperson to identify a multitude of images or optotypes (letters, symbols,characters, figures of different sizes, shapes, orientation).

Visual pursuit testing can be performed with similar targets or visualelements of interest as have been described previously. Smooth pursuittesting has traditionally been performed with the head motionless andthe eyes following a moving light or finger moving across a visualfield. FIG. 11 shows a scene that can be used for scan path tracking. Anenhanced target visual element 940, can travel across the visual scenealong a specific path 942, while the measured eye movement follows thevisual element. The path of these visual images or elements can assumeany pattern, such as a zigzag, a saw toothed, or a square wave, or havea scan path that is snake-like, curved, circular, sinusoidal orrotational to provide a realistic and natural method of assessment ofvisual pursuit.

FIG. 12 shows the relationship between target movement, eye position1601, eye velocity 1603, and eye acceleration for smooth pursuit. Thetime when the target is moved is identified as t=0 ms. The eye position1601, and eye velocity 1603, can then be tracked as a function of time.Latency, 1609, is the delay from the time the target moves to the timethe eye starts to move. Then the eye velocity 1603, will firstaccelerate 1605, and decelerate 1607, until the eye velocity 1603,matches the target velocity.

FIG. 13A shows the relationship between target movement, eye position1701, and eye velocity 1703, for a saccade. The time when the target ismoved is identified as t=0 ms. The eye position 1701, and eye velocity1703, can then be tracked as a function of time. Latency, 1707, is thedelay from the time the target moves to the time the onset of a saccade.As shown, the saccade eye velocity, 1703, increases, reaches a peakvelocity 1705, and then returns to zero. The length of time from thestart to the end of this velocity curve is called the saccade duration1709. The saccade eye position 1701, changes during this duration 1709,to reach a new position that differs from the initial eye position by adistance that can be defined as a saccade amplitude 1711. FIG. 13B showsthe typical relationship between saccade amplitude and saccade duration.

Note that any of the testing described for any of these embodiments canbe done with static targets or visual elements being viewed, or withdynamic targets or elements. The images or elements viewed may befamiliar objects, such as balls, or objects more familiar to one'soccupation or preferred activities. The visual target or visual elementsmay be displayed in a manner that is native or natural to thebackground.

FIG. 14 provides a more generalized embodiment of the system and methodthat was presented in FIG. 2, FIG. 3, and FIG. 4. Referring to FIG. 14,the faceguard unit that was shown at 602, in FIG. 2, FIG. 3, and FIG. 4,is also shown in FIG. 14. The eye tracking video camera on the unit thatwas shown at 608, the display 604 (which could be the visual cue, 434,of FIG. 1 on the surface 432 of FIG. 1, or it could be a flip-downdisplay as described previously), and the head orientation sensor 606,in FIG. 2, FIG. 3, and FIG. 4 is also shown in FIG. 14. As shown in FIG.14, the process can further include the step of choosing a scene 1810,and the choices of scenes can comprise a static scene with a solidbackground 1812, a static scene with a complex background 1814, and/orscene with dynamic (i.e. moving) elements in the background 1816. Theprocess shown in FIG. 14 includes the step of visualizing or projectinga target visual element in the center of the scene or 610 and 620, justlike the processes shown in FIG. 2 (steps 612, 614, and 616), FIG. 3(steps 622, 624, 626), and FIG. 4 (steps 632, 634 and 636).

Further referring to FIG. 14, the method can comprise the step ofchoosing which ocular test to run on a subject as shown at 1820, and thechoices can include ocular performance calibration 1822, static targetand active head movement testing 1824, and/or static target and passivehead movement testing 1826. Each of these three test processes (1822,1824, and 1826) involves measuring eye orientation changes 642 and headorientation changes 640, just like the processes shown in FIG. 12, FIG.13, and FIG. 14. These ocular performance parameters can include any ofthe following parameters that have been discussed in other parts of thisdisclosure, including but not limited to:

(a) vestibulo-ocular reflex;

(b) pupillometry;

(c) saccades (overt and covert);

(d) visual pursuit tracking;

(e) vergence (convergence and divergence)

(f) eyelid closure;

(g) dynamic visual acuity;

(h) dynamic visual stability;

(i) retinal image stability;

(j) foveal fixation stability;

(k) focused position of the eyes;

(l) visual fixation of the eyes at any given moment and

(m) nystagmus

In an alternate embodiment to the configuration shown in step 1824 inFIG. 14, the visual target of interest can be dynamic and the headmovement can also be dynamically moving in the same or oppositedirection as the visual target movement. The process is repeated as manytimes as needed. This test can be conducted in the vertical, horizontalor any other direction.

Regarding the forward-facing camera, shown at 408 in FIG. 1, it shouldbe noted that this scene camera or forward-facing camera 408 can beconfigured to record an image of what the user is seeing. Knowing wherethe subject is looking allows estimating the point-of-regard andoverlapping it onto each video frame. In the embodiments discussedherein, the forward-facing camera 408, can be configured to determine,measure and log where the eyes of an individual, such as an athlete ormilitary person, are looking during their play, occupational or militaryactivities. This can be used to measure the duration of time anindividual is visually focused on an object or target of interest. Forexample, this can measure if an athlete or military person can see anopponent or parts of an opponent (such as the hand or helmet) morequickly in time than others and how long the individual maintains focuson the visual object during the play or activity. This can be correlatedwith the eye tracking video camera 406, for measurement of accuracy andreaction times. Individuals with highly focused ability on the object ofinterest can more accurately anticipate and more precisely predict themovements of their opponents. This data can be used in training and/orthe selection process of individuals prior to performing the activitiesneeded.

Further referring to FIG. 1, the forward-facing camera 408, can beconfigured to adjust its field of view, focal length, or to zoom in orout in response to an eye sensor. The electronic module 410, using thecentral processing unit 418, could control the forward-facing camera408. This control of the forward-facing camera 408, could be throughwired or wireless electronic signals. The forward-facing camera 408,could transmit video information to the electronic module 410, and thisvideo information could analog or digital information and could betransmitted through a wired or a wireless connection. The informationcollected and/or recorded by the forward-facing camera 408, can beresponsive to the eye sensors 406, to measure ocular performanceparameters. For VOR measurement, head rotation information would bemeasured using the head orientation sensor 404. The informationcollected and/or recorded by the forward-facing camera 408, could alsobe used, in conjunction with other information collected by thefaceguard system, for capturing visual images of the user'ssurroundings, and determine the intended focal point of the use. Asdiscussed previously, this determined intended focal point can bemeasured and correlated with the fixation accuracy of the eye trackingsensors. The user can also perform a predetermined action with thehis/her eye(s) by focusing on a specific image or orienting the eye in aspecific manner as an input control. Data collected can be uploaded andtransmitted to a remote or external device.

In an embodiment the forward-facing camera can be configured forrecording video images at a minimum of 24 frames per second. In anotherembodiment, the faceguard can be configured to have an attached visualcue projector, 430 in FIG. 1. This visual cue projector 430 can projecta visual image or visual element, 434 in FIG. 1, in front of the user'svisual field. The forward-visual cue projector 430 can be configured toproject a stable image, for the user to focus upon, while the head is inmotion and it can be configured to provide a moving image when the headis motionless. This visual cue projector 430 can be used for calibrationpurposes or projection of visual elements for testing the ocularparameters discussed herein and for visual rehabilitation followingconcussions/TBIs and the resulting cognitive deficits.

Embodiments of the faceguard invention(s) disclosed herein can beconfigured with a forward-facing camera to determine the point offixation or gaze and can be integrated with an eye sensor configured forsensor fusion to enhance accuracy of gaze determination. Theforward-facing camera can be configured for measuring and correctingslippage offsets as defined previously. This is done by coordinating theeye tracking camera and the head orientation sensor to calculate anyslippage offsets and accurately determine point of visual fixation orthe visual element(s) of eye fixation at a specific time and for aspecific duration. To determine if the gaze position signal is affectedby slippage during recordings, a validation at the end of recordings,and during testing can be done. To avoid further slippage-sensitiveeye-tracking setups, all components (sensors and circuitry) should beevaluated, such as movement of the eye tracker or for VOR measurement,movement of the head orientation sensor. In these embodiments of thefaceguard, sensors are configured for head orientation and eye musclemovement response measurements including but not limited tovestibulo-ocular reflex, pupillometry, saccades, vergence, dynamicvisual acuity, eye-lid closure, focused position of the eyes, kineticvisual acuity, virtual retinal stability, retinal image stability,foveal fixation stability and nystagmus.

Embodiments of the faceguard invention can incorporate other impactmitigation elements and sensing elements/transducers for detecting anyabnormal physiological or biochemical properties of the user.

In the embodiments disclosed herein, the forward-facing camera can beresponsive to the eye sensors to measure the ocular performancedescribed. It can visualize “world” objects in motion and then correlatethese visual objects seen by the user with user eye movements. Measuringthe visual object, the user is focusing upon, can be used to determine aprediction component of the user eye motion based on the visual targetmotion (e.g. Motion Tracking with Predictive Index Factor).

Sensors

Embodiments of the invention(s) disclosed herein utilize sensors. Thesesensors can also be referred to as sensing elements/transducers and/ortransducers. In embodiments disclosed herein, these sensors can be usedto detect and measure specific physical phenomena such as ocularperformance and head orientation. There can also be sensors that measurephysiologic, biochemical, and biometric values. The faceguard canincorporate sensors or sensing elements/transducers. The sensingelements/transducers could be attached or positioned to measure variousproperties of the faceguard. Sensing elements can deploy a response toinput information. One example would be a pneumatic element (e.g.pneumatic/inflation bag, cushion or pad) from the faceguard, which canalter or change its characteristics prior to imminent impact. Thesensing elements, sensors, or transducers can exhibit artificialintelligence in response to imminent blow information detected and themeasured threshold values to determine the abnormal value necessary toelicit a response. These sensing elements/transducers on the faceguardcan be self-altering, self-adjusting and can change the shape orcharacteristics of the faceguard elements before and after an impact toresume the pre-impact state. The sensing elements, sensors, ortransducers can also allow observers to remotely check the status any ofthe sensing elements/transducers described and can change the parametersof the sensing element/transducer measurement or sensitivity if needed.Sensing elements/transducers on the faceguard can record information ofhow many times an impact has occurred to the faceguard and the force ofthe impact to the faceguard. Artificially intelligent sensingelements/transducers can also change a faceguard material characteristicshape and resistance, depending on the impending impact detected.

In another embodiment, the faceguard can be comprised of an impactsensor and an alarm, whereby the alarm is responsive to the impactsensor when an impact threshold has been reached. Whenever a criticalimpact has occurred the alarm will provide a signal indicating a needfor evaluation of the affected athlete. This impact threshold can be avalue to alert the user and others that testing of the user is requiredto determine if there is evidence of a concussion/TBI. The determinedvalue may differ, based on age of the player, sex, ethnicity, locationof the impact and other factors. For many athletes, impacts resulting ina linear head acceleration of 70 to 75 g may be sufficient to result inconcussion. Therefore, the measured impact threshold for the sensor toelicit an alerting signal may be set at 75 g. Specific sensor locationor placement can also be configured on the faceguard in one or morelocations to detect both linear and rotational or tangential impacts.For example, in one embodiment an impact sensor responsive to linearimpacts could be located in the center of the faceguard. An impactsensor responsive to rotational or tangential impacts could be locatedon the side of the faceguard structure. The accuracy of injuryprediction improves with the addition of rotational and linearacceleration variables and the pre-set thresholds may be adjusted fordifferent threshold. These sensors can be adjusted remotely. Forexample, impacts resulting in a rotational acceleration in excess of5582 rad/s² can be associated with 1.9% chance of injury for impactsabove this level. When resultant linear acceleration in excess of 96 gis included in the decision-making process, the possibility of aconcussion increases to 6.9%.

These sensing elements/transducers can be pressure sensitive,ultrasonic, mechanic, electrical, electromagnetic, responsive to haptic,graphene, PVDF (polyvinylidene fluoride sensing, fluid-based sensingelements/transducers, microelectromechanical systems (MEMS)-based onaccelerometers, silicon-based solid-state accelerometers, binary sensingelements of plastic housing and working fluids to detect instantaneousacceleration (impact).

In another embodiment, the abnormally measured physical, physiologicaland/or biochemical parameters can be wirelessly transmitted anddisplayed to an observer and/or provide a local, adjacent or remoteresponse, alert or warning. This response to an abnormal value can be inthe form of an optically perceptible response, such as photofluoresence,or can be a haptic, vibratory, or acoustical, either to the user and/orthe device of the observer. For example, the faceguard or specificportion of the faceguard can change colors, emit a light, display orgenerate another signal response when an abnormal pre-determined impactthreshold to the faceguard is reached, when abnormal oculomotor findingsare measured and/or when an abnormal physiological or biochemicalpre-determined value is measured.

In another embodiment sensing elements/transducers located on thefaceguard can detect where the eyes are looking and focused, which canbe correlated with a forward-facing camera and can log the datastatistics on eye movements and point of fixation of the eyes at anygiven time. These sensing elements/transducers can be configured tomeasure human ocular performance of eye muscle movement responsesincluding the vestibulo-ocular reflex, saccades, visual pursuittracking, pupillometry, vergence, convergence, divergence, eye-lidclosure, dynamic visual acuity, kinetic visual acuity, retinal imagestability, foveal fixation stability, focused position of the eyes orvisual fixation at any given moment and nystagmus. Sensor data acquiredfrom the faceguard can be transmitted to a remote device such as smartwatch, smart phone or tablet, Droid-type hand-held device or otherelectronic device.

In another embodiment, a sensor(s) attached to the faceguard can beconfigured for generating an alarm (output) signal in response toinformation received from the group of eye movement information, eyemuscle movement response information and/or head movement information.For example, if an abnormal VOR is measured an alert signal can begenerated. Similarly, if abnormal saccades, vergence or pupillometryparameters are detected, an alert signal can be generated. These alarmsignals would be in response to any abnormally measured value from theeye sensor information for movements of rotation of a human eyeball,pupil size, eyelid movement and vision. The alarm or alert signal can behaptic, auditory, visual or it can be a wireless message to a remoteelectronic device.

In the embodiments discussed herein, the forward-facing camera, visualcue projector eye and head tracking sensors and components of theelectronic circuit can be activated or controlled haptically,auditorily, remotely, wirelessly, with gestures or movement of the eyes,head, hands or manually with a power switch on the faceguard.Alternatively, the system can have a local/sideline mode (e.g. where thedevice remains on for testing while the player is off the field) and afield mode (e.g. where the device is listening for pre-define triggersalerts, at which time it will be turned on for measurement of ocularparameters).

Eye Tracking

To measure some specific eye responses (such as VOR, saccades, vergenceor other ocular performance measures), both eye tracking and headtracking measurements are required. Eye tracking is the process ofmeasuring either the point of gaze (where one is looking) or the motionof an eye relative to the head position. An eye tracker is a device formeasuring eye positions and eye movement. Eye tracking and/ormeasurement can be done in many ways, examples of which include using aface guard as discussed herein, with eye sensors and a head orientationsensor and having the user look at a projected image in a naturalenvironment;

The eye tracking and/or measurement can also be done:

-   -   (a) in a non-contact fashion with the use of a light source        (invisible light, such as with the use of an infra-red camera or        light, or visible light); and    -   (b) by using a video camera or other imaging sensor system        designed to visually capture and record the eye movement        activity.

If one or more video cameras are to be used for eye tracking, it isdesirable to have a sampling rate at least 60 frames per second (60 Hz)and preferably at least 90-120 Hz. Many video-based eye trackers havesample rate of at least 30, 60, 120, 250, 350 or even 1000/1250 Hz. Inembodiments of the present invention, eye tracking can use a samplingrate minimally of 60 Hz, but more typically at 120 Hz-350 Hz. Thesehigher sampling rates may be needed in order to capture fixation of eyemovements or correctly measure other saccade dynamics or capture thedetail of the very rapid eye movement during reading, or duringneurological evaluations, such as with concussions.

In embodiments of the invention, a light source can be used toilluminate the eye(s) and aid in eye tracking and/or measurement. Thelight source can be directed toward the eye or eyes and a camera tracksthe reflection of the light source and visible ocular features such asthe pupil features and/or cornea surface reflection(s). The informationcan then be analyzed to extract eye rotation and ultimately thedirection of gaze from changes in reflections. Additional informationsuch as blink frequency and changes in pupil diameter can also bedetected by the eye sensor. The aggregated data can be stored andwritten to a file that is compatible with eye-tracking analysissoftware. Graphics can be generated to visualize such findings. Beyondthe analysis of visual attention, stored eye data can be examined tomeasure the cognitive state, fatigue, alertness or other information.

As noted previously, a video camera or image sensor can be attachedanywhere on or in the framework elements of the faceguard. The cameracontrol unit can be activated by such options as: an auditory humaninput signal, a haptic human input signal, a digital auditory inputsignal, a digital haptic input signal, a manual input signal, human eyemuscle movement or a human gesture. The control unit can also be timeractuated or triggered by an eye blink for a defined period of time.

The eye tracking and/or measuring system may include hardware such as aninfrared camera and at least one infrared light source, a video trackingsystem and recorder or data logging unit. The infrared camera may beutilized by the eye tracking system to capture images of an eye of thewearer. The video images obtained by the infrared camera regarding theposition of the eye of the wearer may help determine where the wearermay be looking within a field of view of the head mounted display usedin the system. The infrared camera may include a visible light camerawith sensing capabilities in the infrared wavelengths. Infrared light orradiation is a longer-wavelength radiation than visible light. It existsjust outside of the spectrum of visible light. Heat, or thermal energy,is a common source of infrared light. An infrared camera is a devicespecially designed to detect and display the sources of this kind oflight. A thermal infrared camera converts the heat detected intoelectrical signals, which are then projected in an image. Many types ofnight vision cameras are based on infrared light. A human body willalways emit heat, and infrared cameras will detect this radiation.

The infrared light source can include one or more infraredlight-emitting diodes or infrared laser diodes that may illuminate aviewing location, i.e. an eye of the wearer. Thus, one or both eyes of awearer of the system may be illuminated by the infrared light source.The infrared light source may be positioned along an optical axis commonto the infrared camera, and/or the infrared light source may bepositioned elsewhere. The infrared light source may illuminate theviewing location continuously or may be turned on at discrete times.

In embodiments of the invention, a display device, such as a smartphone, can be mounted onto the faceguard and the optical system of thedevice can include components configured to provide images to an eye ofthe wearer. The components may include an attached display pane, adisplay light source which can display a visual element or scene capableof being stable or in motion and the image sensors and head trackingsensors attached to the faceguard can measure the ocular parametersdiscussed by observing the visual element or scene displayed. Thesecomponents may be optically and/or electrically coupled or wirelesslyconnected to one another and may be configured to provide viewableimages to the user's eye. One or two optical systems may be provided inthe system.

Eye sensors which track different locations on the surface of one orboth eyes or using multiple illumination sources and/or multiple camerasto generate and observe glint/reflections from multiple directions canbe used to improve the accuracy of gaze tracking. One or more of theillumination sources can be comprised of infrared, near infrared orvisible light, such as a micro-LED or micro-OLED projector. Eye sensorscan be used to obtain anatomic structures and features of the eye,movements of the eye and eyelids, responses and reflexes of the eyes andeyelids. Eye tracking data can also be collected using a multi-cameraeye gaze tracker, which is based on one-camera gaze estimationalgorithm. Using an algorithm, the 3D eyeball position can be estimatedby the two corneal surface reflections (or glints) of the IR lights.Each camera can estimate the gaze independently and can allow large headmovement. The system can be accurate to less than 1 degree.

In an embodiment, the human ocular performance measuring system iscomprised of eye sensors, attached to the faceguard unit, and configuredto measure eye muscle movement responses using different techniques ofeye sensor measurement including, but not limited to use of one ormultiple cameras, or simultaneous use of different types of cameras foreye tracking. Alternatively, eye sensors can track of one or moredifferent locations simultaneously on the surface of one or both eyes(e.g. cornea, pupil, limbus, sclera) or image features from the retina.In another embodiment, the eye sensor(s) measure more than one cornealreflection or other eye feature using one or more different types ofillumination sources simultaneously. The different types of illuminationsources can also alternate or combine the type of illumination,depending on the light needed. Positioning of the camera, or cameralocation which records the eye features is crucial and depends on lightconditions and in another embodiment, the position of the eye camerascan change.

Eye sensor or image sensor data collection can be based onambient/natural light, infrared, near infrared or non-traditionalmethods such as ultrasonic or by pulsed laser light. The software usedto capture the data is often selected on the basis of the final imageresult needed or desired when viewing images in motion. One approach isthe use of a global shutter which captures an entire frame all at once.Image sensors with a global shutter allow all of the pixels toaccumulate a charge with the exposure starting and ending at the sametime. At the end of the exposure time, the charge is read outsimultaneously. In turn, the image has no motion blur on moving objects.A rolling shutter is much different and unlike a global shutter wherethe sensor is exposed all at once, a rolling shutter is exposed in aprogressive motion. Image sensors with a rolling shutter do not exposeall the pixels at the same time. Alternatively, they expose the pixelsby row with each row having a different start and end time frame. Thetop row of the pixel array is the first to expose, reading out the pixeldata followed by the 2nd, 3rd & 4th row and so on. Each of the rows, atthe beginning and end point, have a delay as the sensor is fully readout. The result of this on moving objects is a skewed image.

In another embodiment, eye sensors, attached to the faceguard unit canbe located in different positions to acquire different focal points ofthe eyeball, to achieve more accuracy with eye tracking. Eye sensors canalso be configured to merge eye movement responses from different imagesensors for more accurate measurement. For example, an eye sensortracking the bright pupil can be merged with the same sensor, or anothereye sensor, attached to different location on the faceguard, which istracking the dark pupil response. In another example, an eye sensortracking the dark pupil can be merged with the same or different sensorwhich is tracking the limbus. The merged data can provide moreinformation regarding gaze and eye muscle movement responses. Eyesensors can have multiple functions which enable different measurementor features of the eyeball.

Eye tracking using binocular horizontal and vertical eye positionestimates can be derived from the relative positions of multiple cornealreflections and the center of the pupil. By using two eye landmarks(corneal surface reflections and pupil center) whose relative positionare invariant under translation, the angular position of the eyeindependently of lateral motion of the video system relative to the headis able to be estimated. The eye sensors used to measure different eyelandmarks can be mounted on a faceguard in another embodiment.

In embodiments of the invention, the light source can be infrared, nearinfrared, and/or visible light, such as LED, can be directed toward oneor both eyes and one eye could have one light source which is differentthan the light source directed toward the other eye. The camera can beused to track the reflection of the light source and visible ocularfeatures such as the pupil features, cornea reflection features, irisregistration features, limbus features or retinal data imaging. Thecollected data from the eye tracking system can be used to measure themuscle movement responses of the eyes or eyelids or rotation of theeyeball, acceleration/velocity of the eye movement, duration of theeyelid closure, rate of the eyelid closure and the direction of gaze.Additional information such as blink frequency and changes in pupildiameter can also be detected by the eye tracker. Aggregated eye trackerdata can be written to a file for later analysis. Stored eye trackerdata can be used to analyze the visual path across an interface such asa computer screen. In this case, each eye data observation is translatedinto a set of pixel coordinates. From there, the presence or absence ofcollected eye data points in different screen areas can be examined.This type of analysis is used to determine which features are seen, whena particular feature captures attention, how quickly the eye moves, whatcontent is overlooked and virtually any other gaze-related data. Eyeposition is extracted from video images and graphics are often generatedto visualize such findings. When using a video-based eye tracker, thecamera can be focused on one or both eyes and used to record eyemovement as a viewer looks at some type of stimulus.

The video camera or image sensor can be attached to the faceguard andpositioned anywhere around the eye (e.g. under, above, or to the sides)or directly positioned in front of the eye, and directly in the visualfield, depending on which eye movement characteristic is being measured.In an embodiment, at least one eye sensor is positioned below theinferior margin of the upper eyelid, in order to measure thecharacteristics of the eyeball. It is below the upper eyelid in order tomore easily visualize the pupil, cornea, iris or other features of theeye used for eye tracking. In this position, the upper eyelid andeyelashes would not obstruct the eye muscle measurements related to therotation of a human eyeball or vision and the visual measurements. Itallows for unencumbered measures of the ocular parameters. Eye sensorsabove the inferior margin of the eyelid can measure eyelid movement,specifically eyelid muscle motion, movement above the levator muscle andbehavioral feature characteristics.

When using an eye-tracking camera, two general types of eye trackingtechniques can be used: Bright Pupil and Dark Pupil. The dark and brightpupil tracking techniques are based on the iris-pupil boundarydetection. Light sources in the near IR spectrum are often used forthese two approaches. The difference between these eye-trackingtechniques is based on the location of the illumination source withrespect to the optics. In the bright pupil approach, the infrared sourceis placed near the optical axis, while in dark pupil it is placedfarther away from this axis. Therefore, in the bright pupil approach,the video camera records the infrared beam reflected by the subject'sretina, making the pupil brighter than the iris, while in the dark pupilapproach, the reflected infrared beam is not recorded by the camera andthe pupil becomes darker than the iris. For the bright pupil approach,the infrared illumination is coaxial with the optical path and the eyeacts as a retro-reflector as the light reflects off the retina creatinga bright pupil effect similar to red eye. If the illumination source isoffset from the optical path, as described for the dark pupil approach,then the pupil appears dark because the retro-reflection from the retinais directed away from the camera. Bright Pupil tracking creates greateriris/pupil contrast allowing for more robust eye tracking with all irispigmentation and greatly reduces interference caused by eyelashes andother obscuring features. It also allows for tracking in lightingconditions ranging from total darkness to very bright. But bright pupiltechniques are not effective for tracking outdoors as extraneous IRsources interfere with monitoring. In the preferred embodiment, thesystem is configured to measure an eye parameter selected from the groupof bright and dark pupil measurements. These tracking techniques can beuse simultaneously or depending on the ambient light levels thetechniques can alternate or alternatively, one eye may be tracked withone technique and the other eye can be tracked by the other technique.

Embodiments of the eye tracking system can track on the cornea orfurther in the eye, based on using light reflected by the eye. Whetherusing an external source or ambient light, some of the techniques fortracking the eye include not only pupil tracking, but also limbustracking, Purkinje image tracking, corneal and pupil reflectionrelationship, corneal reflection and eye image using an artificialneural network.

Regarding limbus tracking, the limbus is the boundary between the whitesclera and the dark iris of the eye. Because the sclera is (normally)white and the iris is darker, this boundary can easily be opticallydetected and tracked. The limbus tracking technique is based on theposition and shape of the limbus relative to the head. This means thateither the head must be held still, or the apparatus must be fixed tothe user's head. Due to the occasional covering of the top and bottom ofthe limbus by the eyelids, it is more helpful for precise horizontaltracking only.

Regarding pupil tracking, this technique is similar to limbus tracking.The difference is that in pupil tracking the smaller boundary betweenthe pupil and the iris is used instead of the boundary between the whitesclera and the dark iris. The advantages of this technique over limbustracking is that the pupil is far less covered by the eyelids than thelimbus, and thus vertical tracking can be accomplished in more cases.Also, the border of the pupil is often sharper than that of the limbus,which yields a higher resolution. The disadvantage pupil tracking isthat the difference in contrast is lower between the pupil and iris thanbetween the iris and sclera, thus making border detection moredifficult. As noted previously, there are different illumination methodsthat can be used with pupil center corneal reflection eye tracking.Bright pupil eye tracking is achieved when an illuminator is placedclose to the optical axis of the imaging device and dark pupil eyetracking occurs when an illuminator is placed away from the optical axiscausing the pupil to appear darker than the iris.

Video-based eye trackers typically use the corneal reflection (the firstPurkinje image) and the center of the pupil as features to track overtime. A more sensitive type of eye tracker, the Dual-Purkinje eyetracker uses reflections from the front of the cornea (first Purkinjeimage) and the back of the lens (fourth Purkinje image) as features totrack. A still more sensitive method of tracking is to image featuresfrom inside the eye, such as the retinal blood vessels, and follow thesefeatures as the eye rotates. Different factors can affect the pupildetection during eye tracking and eye trackers using multiple methods,such as dual-Purkinje or both bright and dark pupil methods can be moreaccurate in calculating the gaze position.

Other methods to track the eye are based on the visible images of abright source that can be seen reflected from the structure of the eye.These images are called Purkinje images. The dark pupil/bright pupiltechniques which were previously discussed can be used in combinationwith one of these methods, called the corneal reflection method. Onetype of video-based eye tracker tracks the reflection of the light onthe outer surface of the cornea (first Purkinje image or often referredas glint) and the center of the pupil as features to track over time.The reflection appears as a very bright spot on the eye surface thus, itcan be detected easily. Under some assumptions, the glint positiondepends only on head movement, thus the gaze can be estimated by therelative position between the glint and the pupil center. A moresensitive type of eye tracker, the dual-Purkinje eye tracker, usesreflections from the front of the cornea (first Purkinje image) and theback of the lens (fourth Purkinje image) as features to track. DualPurkinje method is based on tracking both the first and the fourthPurkinje images. The fourth Purkinje image is formed by the lightreflected from the rear surface of the crystalline lens and refracted byboth cornea and lens itself. These two Purkinje images move together forpure translational movement but, once the eye undergoes rotation, theirdistance changes, giving a measure of the angular orientation of theeye. When light (such as infrared) shines into the user's eye, severalreflections occur on the boundaries of the lens and cornea and is sensedby a video camera or eye sensor. These reflections or Purkinje imagescan then be measured and analyzed to extract eye rotation data fromchanges in reflections. In a preferred embodiment, the system isconfigured to measure an eye parameter selected from bright pupil/darkpupil measurements in combination with Purkinje measurements, includingdual Purkinje and/or first Purkinje image measurements. In anotherembodiment, the system is configured to measure an eye parameterselected from Purkinje measurements, including dual Purkinje and/orfirst Purkinje image measurements.

Regarding pupil and pupil reflection relationship tracking, eye trackerscan combine a camera with an infra-red light source that illuminates theeye with bursts of invisible infra-red light. Some of this infra-redlight disappears into the pupil (the dark opening in the center of theiris), and some of it bounces back off the iris (the colored part of theeye), the cornea (the clear part at the front of the eye), the eyelid orthe surrounding skin. All these different areas reflect differentamounts of infra-red light, which is picked up by the camera. Byanalyzing the reflections, it is then possible to determine where theeye is pointing. The technique is able to cope with blinking, headmovements, dim light, glasses and contact lenses.

Regarding the use of artificial neural networks (ANNs) for computation,this is of the more recently developed techniques. The raw material foreye-gaze tracking is still a digitized video image of the user, but thistechnique is based on a more wide-angled image of the user, so that theentire head is in the field of view of the camera. A stationary light isplaced in front of the user, and the system starts by finding the righteye of the user by searching the video image for the reflection of thislight—the glint, distinguished by being a small, very bright pointsurrounded by a darker region. It then extracts a smaller, rectangularpart of the video image (typically only 40 by 15 pixels) centered at theglint, and feeds this to an ANN. The output of the ANN is a set ofdisplay coordinates. The ANN requires more than the simple calibrationthat is required by the other techniques; it must be trained bygathering images of the user's eye and head for at least three minuteswhile the user visually tracks a moving cursor on the display. This isfollowed by an automatic training session that uses the stored imageslasting approximately 30 minutes using the current technology, but thenthe system should not require re-calibration on the next encounter. Toimprove the accuracy of an ANN-based system, the corneal/pupil-basedcalculations can be augmented with a calculation based on the positionof the glint in the eye socket. The advantage of ANN-based techniques isthat due to the wide angle of the base image, user head mobility isincreased.

Eye movement information from the eye tracker can be typically dividedinto fixations and saccades, when the eye gaze pauses in a certainposition, and when it moves to another position, respectively. Theresulting series of fixations and saccades can be called a called a scanpath. Most information from the eye can be made available during afixation, but not during a saccade. The central one or two degrees ofthe visual angle (the fovea) can provide the bulk of visual information;the input from larger eccentricities (the periphery) is typically lessinformative and analysis algorithms can be structured accordingly.Hence, the locations of fixations along a scan path show whatinformation loci on the stimulus are processed during an eye trackingsession.

Scan paths are useful for analyzing cognitive intent, interest, andsalience. Other biological factors (some as simple as gender) may affectthe scan path as well. As a participant looks at a page on the internet,the eye-tracking device can focus on the pupil of the participant's eyeand determine the direction and concentration of the participant's gaze.Heat maps determine where an individual concentrated their gaze and howlong they gazed at a given point. Saccade pathways trace the eye'smovement between areas of focus. The movement is not unlike watching ahummingbird move between flowers—there are periods of attention and thenrapid movement.

Another capability of the eye tracking technology is eye movementanalysis, which can provide valuable insight into user's overt visualbehavior and attention. The most common method for determining thelocation of a user's observable visual attention is by identifying thefixations and saccades that best indicate where they are focusing on thestimulus in front of them.

A linear filter may be used when processing eye-tracking data toapproximate eye movement signals, at least well enough to recognize apattern. The salient eye movements that are typically identified by eyemovement analysis are fixations, saccades (overt and covert), and smoothpursuits. Fixations are a result of one's desire to maintain gaze on aspecific, stationary object. Smooth pursuits are similar except for theobject of interest is in motion. Saccades represent a voluntary shift offocus from one fixation point to another.

Saccades can be detected and measured by two means as well: the positionvariance method and the velocity detection method. The position variancemethod identifies saccades as those moments in the signal in which theposition of the eye changes rapidly. The velocity detection method usesan empirically determined velocity threshold. If the velocity of thesignal is calculated as higher than the threshold, it is a saccade.Similarly, if it is below the threshold (as discussed above) it is afixation. For both fixations and saccades, the velocity method is oftenmore widely used because it is more suitable for real-time applications.

Beyond the analysis of visual attention, eye data can be examined tomeasure fatigue, the cognitive state and workload of a person. Sometechniques have been validated in multiple contexts as a reliableindicator of mental effort. Driving a car, reading a magazine, surfingthe internet, searching the aisles of a grocery store, playing a videogame, watching a movie or looking at pictures on your mobile device aresuch applications of eye tracking. With very few exceptions, anythingwith a visual component can be eye tracked.

In embodiments of the present invention, saccades can be tested bypositioning two widely spaced targets in front of the person and askingthe person to look back and forth between the targets. The technologyused in faceguard can be used to calculate corrective saccades. Thissystem for the person is configured to collect eye images of the personin excess of 60 Hz and configured to resolve eye movements smaller thanat least 3 degrees of motion. Eye movement data can include at least onefixation target presented to the subject in a defined position andconfigured to yield a voluntary saccadic eye response from at least oneeye of the person. The latency, amplitude, accuracy and velocity of eachrespective corrective saccade and latency totals and accuracy iscalculated. This platform can calculate, and display secondary, andhigher, corrective saccades. Calculating corrective saccade measurementsfrom the eye data can include:

-   -   (a) the total number of corrective saccades associated with the        subject's eye movement to each fixation;    -   (b) first corrective saccade latency;    -   (c) first corrective saccade amplitude;    -   (d) first corrective saccade accuracy;    -   (e) first corrective saccade velocity;    -   (f) ratio of first corrective saccade amplitude to main saccade        amplitude associated with the subject's eye movement to each        fixation target; and    -   (g) ratio of total of corrective saccade amplitudes to main        saccade amplitude associated with the subject's eye movement to        each fixation target presented to the subject.

The corrective saccade measurements can include measurements for a firstcorrective saccade and at least a second corrective saccade. Thecorrective saccade measurements for each corrective saccade can includethe latency, amplitude, accuracy and velocity of each respectivecorrective saccade. During the initiation of a saccade, a high framerate may be required for complete assessment.

Dynamic visual acuity (DVA), and retinal image stability (RIS), andfoveal visual stability (FVS) testing can be used to determine thecondition of a person's vestibulo-ocular reflex function. A DVAassessment can also include identifying a series of images or optotypesbut with the addition of a head movement along an axis at a minimumrotational rate, engaging the vestibular system. The visualized imagesmay also be dynamically moving in any direction, and can be random inposition, appearance and presentation. Specifically, the image or visualelement to be identified can be seen coming from any direction, randomlyor with a specified pattern of motion, and may have different shapes,features, colors, sizes, orientation, patterns, or identifyingcharacteristics, in a specific plane of axis or in variable plane, whichthe person must identify while the head in motion or rotating. Theperson can then provide feedback regarding what they see via anon-screen gesture, keyboard, smart device (e.g. defined as an electronicdevice, generally connected to other devices or networks via differentwireless protocols such as Bluetooth, NFC, Wi-Fi, 3G/4G/5G cellular,etc., that can operate to some extent interactively and autonomously),eye or other physical response or by voice response. The comparison ofthe smallest image, visual image or optotypes correctly identified orthe comparison of the correct numbers of images, visual elements oroptotypes in both the DVA and SVA tests can determine if the person hasa defect in his or her vestibulo-ocular reflex functions.

Faceguard embodiments of the present invention can have the advantage ofmeasuring smooth pursuit (e.g. pursuit tracking during visual pursuit)in any plane, at various frequencies and in a variety of scan paths. Asan example, eye tracking and visual or smooth pursuit can be done byvisually observing a moving image traditionally in a horizontal orvertical plane or alternatively in a saw-tooth, sinusoidal, square-wave,snake-like, torsional, looped or other non-fixed plane of motion, whichis more natural to what the normal person experiences in everyday life.Convergence movements can be evaluated by having the person fixate on anobject as it is moved slowly towards a point right between the person'seyes. Vergence is an oculomotor function, described as disconjugatemovement of the eyes to track images varying in depth over the binocularvisual field and is commonly affected following concussions and mTBI.Embodiments of the present invention can measure this by presenting avisual object to the subject and detecting and measuring the position ofthe eyes and pupil area parameter. The visual object can move linearlyor in sinusoid or another scan path toward and away from the subject at0.1-2 Hz. The responses from both eyes are analyzed and compared todetermine the coordination. In addition, the eyes can be observed andmeasured at rest to see if there are any abnormalities such asspontaneous nystagmus, disconjugate gaze (eyes not both fixated on thesame point) or skew deviation (eyes move upward (hypertropia), but inopposite directions, all resulting in diplopia (double vision).

In embodiments of the present invention, pupillometry tests can easilybe observed with the technology within the elements or attached to thefaceguard elements. Pupil measurements can be calculated independentlyfor each eye when visualizing an image stimulus and the responses can becompared. Pupil measurements can include: pupil diameter with visualstimulus and after stimulus, average pupil constriction velocity,average constriction latency, average pupil dilation velocity, maximumpupil constriction and dilation velocity, pupil constrictionacceleration, and pupil dilation acceleration. The faceguard technologycan allow the pupil to be measured on each side with variation of thelevels of light. Both eye movement and peripheral vision testing can bemeasured. Eye movement testing can also be called extra-ocular musclefunction or response as it represents testing or examination of thefunction of the eye muscles. These tests observe the movement of theeyes in six specific directions. Peripheral vision testing is alsocalled visual field testing. Testing the visual fields consists ofconfrontation field testing, in which each eye is tested separately toassess the extent of the peripheral field. Target detail within theperipheral field-of-view can be altered without attracting attention. Ina process known as “change blindness,” it is also difficult to discernvisual changes (that attract attention) if the changes are introducedslowly or at times when an observer is not looking.

In embodiments of the present invention, the eye or image sensortechnology in the faceguard can be configured to:

-   -   (a) collect eye images in excess of 90 Hz;    -   (b) resolve eye movements smaller than at least 3 degrees of        motion;    -   (c) measure eye muscle movement responses, when a stimulus is        presented to only one eye of the subject or both eyes;    -   (d) yield a pupil movement response from at least one eye of the        person;    -   (e) measure pupils in each eye independently for the person's        left and right eyes; and    -   (f) compare pupillometry measurements for the left and right        eyes.

Another embodiment involves dynamic control of the frame rate (i.e.,number of images acquired per unit of time) of the one or more camerasthat view regions of one or both eyes. Camera frame rate is a majordeterminant of the ability to determine and measure rates and directionsof movement (i.e., velocities) of objects within images of an eye. Themuscles within the eye are capable of movements that are most rapid ofall muscle movements within the human body. Thus, increased camera framerate can be critical in some cases to more accurately and robustlymeasure dynamic movements of an eye and/or its components. Moderncameras are capable of operating over a wide range of frame rates.Instantaneous frame rates can also be adjusted (i.e., governed byso-called “clock” circuitry) as frequently as on an image-by-imagebasis. Closely aligned with camera frame rate is the acquisition timerequired to collect each image. The maximum time a camera can take toacquire an image is the inverse of the frame rate (i.e., the total timeof a frame=1/frame rate). However, modern-day digital cameras also havethe ability to limit the time over which they detect photons during theimage acquisition process. Limiting the time to acquire photons is knownin the art as “electronic shuttering.” Shuttering light (includinginfrared) collection times to very brief intervals (typically in theorder of microseconds to milliseconds) “freezes” images, allowing aclearer view of moving objects since object edges are spread over fewerpixels. On the other hand, longer acquisition times allow the detectionof more photons during each image, increasing the amplitude (i.e.,intensity within each pixel) of camera images and generally increasingsignal-to-noise ratios. Although micro-movements can be useful to infersome aspects of a user's status, they can interfere with directional anddistance measurements of smooth pursuit and voluntary saccades. Higherframe rates allow algorithmic approaches to compensate formicro-movements by removing oscillations/movements at such frequenciesor other mathematical approaches such as averaging results. Briefacquisition times can also be used to reduce image blur associated withmicro-movements. The key to accurately determining initial saccadicdirection and speed is the acquisition of camera images at high framerates (typically hundreds of frames per second). Several techniques areavailable to acquire a rapid sequence of images immediately following asaccadic launch: 1) Once a saccadic launch is detected when sampling ata lower frame rate, the camera is immediately switched to a higher framerate. 2) Camera circuitry (only) can be constantly run at a high framerate, storing images within a circular buffer. Not all images aretransferred out of the camera buffer and processed during normaloperations. When a saccade is detected, rapidly sampled images that hadbeen stored in the camera buffer can be retrieved for processing. 3)Frame rate can be adjusted based on the “context” of eye signal control.High frame rates can be maintained throughout these sequences.

Embodiments of the invention can use miniature video cameras. The imageof the eye can be tracked and allow the person's horizontal, vertical,and/or torsional (rotary) vestibulo-ocular responses or other musclemovement responses to be measured. A moving visual target or visualelement can provide a method for tracking, for optokinetic (OPK)testing, for saccade detection and measurement, for gaze fixationtesting, for DVA measurement and for VOR testing. In the Active HeadRotation (AHR) horizontal test, the subject moves their head left andright randomly to the auditory signal and visual presentation. The speedof the signals increases through 1 Hz up to a maximum of at least 5-6Hz. The person will attempt to keep moving the head back and forth atthe speed of the cueing provided. For AHR Vertical, this test isconducted in the same manner as the horizontal test above, except thatthe head motion is up and down rather than left and right

In further embodiments, the faceguard can include at least one, andtypically two, digital, video or image sensor camera(s) trained on theperson's eyes and which the camera can have auto-tracking. Each cameracan be connected to and/or powered by a computer, such as through a“firewire” type connection. The computer may be a laptop portablecomputer or other digital device. The digital or other cameras may allowfor digital centering of the person's pupil at least in one directionthrough concentrating on the region of interest, and can be in multipledirections. The use of digital centering eliminates the need for amechanical adjustment mechanism in the given direction.

In another embodiment, the eye sensor can be further configured tocapture a 3D image of the iris. In another embodiment, the eye sensorcan be comprised of an array of transparent light detectors based ongraphene. In another embodiment, the system can include an illuminatorthat is configured to provide illumination in a visible, LED or infraredlight spectral band for the eye sensor to capture the 3D image of theiris. In further embodiments, the eye sensor can be a microlens arraylight field camera (LFC) or plenoptic camera.

In embodiments of the present invention, eye movements, muscle movementresponses or reflexes and head movements can be detected and measured ina manner that is novel and unique compared to what has been donetraditionally in the clinical laboratory. These faceguard embodimentsenable a higher level of testing and measurement for these eyeresponses, particularly for the VOR, pursuit tracking, vergence,pupillometry and DVA. Embodiments of the present invention also provideunique methods to rehabilitate persons with vestibular system disorders,particularly those with peripheral vestibular disorders and especiallythose persons with vestibulo-ocular reflex abnormalities and/orabnormalities of ocular parameters discussed herein.

In another embodiment, the images or visual elements projected for thespecific ocular parameter tests can be configured to a plurality ofdepth planes provided to an attached viewer on the faceguard display.The target image or visualized element may be different for each depthplane, which can provide a slightly different presentation of a scene orobject. The target or visual element may be separately focused by eachof the viewer's eyes, to provide depth cues based on the accommodationof the eye required to bring into focus different image features for thescene or visual element located on different depth planes and/or basedon observing different image features on different depth planes beingout of focus. These depth cues can provide credible perceptions of depthand add complexity to the testing and measurement.

Head Tracking

Head tracking on a faceguard can be performed by using an inertialsensing measurement unit (also called an IMU or ‘tracker’). An IMU is anelectronic device that measures one or more degrees of freedom (DOF),such as position, velocity, orientation, and/or gravitational force, aswas described previously in this disclosure, by using one or moresensors. Sensors used in IMUs can include one or more accelerometers,gyroscopes, and magnetometers. A MEMS (micro-electromechanical system)gyroscope, a MEMS accelerometer, and a MEMS magnetometer can be used ascomplementary and/or redundant sensor to accurately support a full rangeof motion in a three-dimensional space. Accelerometers work well formeasuring five DOF: linear movements in three axes; and absolute tiltabout the two axes perpendicular to gravity (i.e. pitch and roll).Accelerometers cannot easily measure rotation about an axis aligned withgravity (i.e. yaw). Magnetometers work well for measuring absolute yawproviding a sixth DOF. Gyroscopes provide a stable way to measurechanges for the three rotational DOF (pitch, roll, and yaw). Devicesthat measure these three displacements and measure each of the threerotations in two different ways are typically called nine DOF IMUs. Theinput signals from the accelerometer(s), magnetometer(s), andgyroscope(s) in these nine DOF IMUS are often processed using a Kalmanor a Madgwick filter located in a sensor pre-processing unit to provideoutput signals that have been optimized for accuracy, stability, andresponse rate.

The head tracking inertial system can be mounted in numerousconfigurations. Examples include: within a faceguard or attached to afaceguard

Fourier Analysis

A Fourier transform can be used to convert the relationship between aninput (such as head motion) and an output (such as eye movement) in thetime domain to a relationship in the frequency domain. By doing this,the ocular parameters discussed herein, can be measured for naturalmotion in a non-clinical environment. As described previously, one ofthe traditional ways of measuring VOR has been to oscillate a subject'shead at a fixed frequency and then to measure how quickly the eyesrespond. For this kind of testing, a frequency of 0.5 Hertz wouldcorrespond to one cycle every 2 seconds. A cycle corresponds to thecombination of one movement to the right and one movement to the left.These movements are typically in the form of a sine wave. The gain atthis frequency would be the amount of compensation that the eyes make tothe movement of the head. A gain of −1 (also often written as a gainof 1) is perfect because the eyes have rotated exactly the same angle asthe head, but in the opposite direction. A gain of −0.75 (often writtenas 0.75) means that the eyes only compensated for 75% of the headrotation. The phase or phase lag describes how much later the eyes movedthan the head. A phase or phase lag of 0 would mean the eyes followedexactly. A phase or phase lag of 45 degrees at a frequency of 0.5 Hertzmeans that the eyes were delayed by ⅛^(th) of 2 seconds (or 250milliseconds) because 45 degrees corresponds to ⅛th of a full 360-degreecycle. To determine gain and phase at a variety of frequencies using thetraditional approach of oscillating the head in a clinical environment,one would repeat the above test at a variety of frequencies and recordthe results. This method requires control over each input frequency andmeasuring the gain and phase of the eye response separately for eachfrequency, which will not work in a non-clinical setting having naturalmotion.

A time-varying signal (such as the natural motion of an object in onedimension) can be converted to a series of sine waves. This conversionfrom a time-varying signal to a series of sine waves is called a Fouriertransform. Fourier transforms can be discrete or continuous. Acontinuous Fourier transform is one in which the time-varying signal isconverted to an entire range of frequencies with no gaps between thefrequencies. A discrete Fourier transform is one in which thetime-varying signal is converted to a specific set of frequencies, suchas the series 0.125 Hz, 0.25 Hz, 0.5 Hz, 1.0 Hz, and 2.0 Hz. DiscreteFourier transforms are easier to calculate using digital electronics. Byconverting the observed natural yaw of the head as a function of timeusing a Fourier transform, one can generate a graph showing theamplitude of the input signal that the eyes would need to compensate forin order to follow a stationary image or visual element. By convertingthe sensed horizontal movement of the eyes at this same time using aFourier transform, one can generate a second graph showing the amplitudeof the eye signal that compensates for the head movement. By comparingthese two graphs mathematically, it is possible to determine gain atvarious frequencies directly from the natural head yaw movement. Similarmathematical calculations can be made to determine phase. The samemethod can be used to determine gain and phase in other dimensions suchas pitch of the head versus the sensed vertical movement of the eyes,etc. Discrete Fourier transform calculations of this type can beperformed by a microprocessor that receives the time-varying orientationsignals from a head orientation sensor and the time-varying signals froman eye orientation sensor using mathematical calculations capable ofbeing understood by anyone skilled in the art.

It should be noted that embodiments of the present invention can beimplemented using dynamic analysis tools other than or in addition toFourier Transform analysis, examples of which can include regressionanalysis, multi-variable regression, band pass filters, time domainanalysis, Bode plots, Nyquist plots, waterfall diagrams, Campbelldiagrams, resonance analysis, power spectral density analysis, frequencyresponse function, coherence analysis, correlation analysis, cross powerspectrum analysis, impulse response analysis, octave analysis, orderanalysis, waveform analysis, and/or any other dynamic system analysistool capable of being understood by those skilled in the art.

Other Potential System Elements

In the preferred embodiment, the faceguard can be configured for eyetracking and measuring, head tracking, a power supply, amicro-processor, a memory, and a user interface. Components of thesystem can be configured to work in an interconnected fashion with eachother and/or with other components coupled to respective systems. Forexample, the power supply can provide power to all the components of thesystem. The processor can receive information from the eye camera/imagesensor signal processor, the head orientation signal processor, forwardfacing camera interface and any peripherals.

The system may include or be coupled to peripherals, such as a wirelesscommunication interface, a touchpad, an integrated microphone, a highdefinition (HD) camera, electronic device and/or a speaker. A wirelesscommunication interface may use 3G, 4G, 5G cellular communications, suchas Code-division multiple access (CDMA), Evolution-Data Optimized(EVDO), Global System for Mobile communication (GSM)/General packetradio service (GPRS) communication or other cellular communications,such as Worldwide Interoperability for Microwave Access (WiMAX) or longterm evolution (LTE). Alternatively, wireless communication interfacemay communicate with a wireless local area network (WLAN), for example,using Wi-Fi. In some examples, wireless communication interface maycommunicate directly with a device, for example, using an infrared link,Bluetooth, near field communication, or ZigBee. In addition, otherwireless interface communication can be used with “off-the-grid”networks (such are FireChat) where there is not cellular phone serviceor internet connection.

The power supply may provide power to various components in the systemand may include, for example, a rechargeable lithium-ion battery, solarpower, mechanical power or various other power supply materials andtypes known in the art.

The processor may execute instructions stored in a non-transitorycomputer readable medium, such as the memory, to control functions ofthe system. Thus, the processor in combination with instructions storedin the memory may function as a controller of the system. For example,the processor may control the wireless communication interface andvarious other components of the system. In other examples, the processormay include a plurality of computing devices that may serve to controlindividual components or subsystems of the system. The processor, inconjunction with the memory unit, may perform analysis of the imagesobtained by the infrared camera.

In addition, the memory unit may store data that may include a set ofcalibrated wearer eye pupil positions and a collection of past eye pupilpositions. Thus, the memory may function as a database of informationrelated to gaze direction. Calibrated wearer eye pupil positions mayinclude, for instance, information regarding extents or range of an eyepupil movement (right/left and upwards/downwards), and relative positionof eyes of the wearer. For example, a relative position of a center andto one side with respect to a gaze direction or a gaze angle of the eyepupil of the wearer may be stored. Also, locations or coordinates ofstarting and ending points, or waypoints, of a path of a moving objectdisplayed, or of a static path (e.g., semicircle, Z-shape etc.) may bestored on the memory unit.

The system may include the user interface for providing information tothe wearer or receiving input from the wearer. The user interface may beassociated with displayed images, a touchpad, a keypad, multiplecameras, buttons, a microphone, a haptic device, and/or other peripheralinput devices. The processor may control functions of the system basedon input received through the user interface. The system and/or testingfunction controls and input connections can be configured to be withinor attached to the faceguard elements and/or in a remote electronicdevice. The faceguard technology system can be activated or controlledwith methods including but not limited to a manual electronic keypad,voice activation, haptic movement, gestures, eyelid movement, ocularorientation, any body movement, visual input and with remote inputsignals. The computing system could be a distributed computing system.The computing system could comprise cloud computing.

One or more of the described functions or components of the system maybe divided up into additional functional or physical components orcombined into fewer functional or physical components. For example, theinfrared camera may be mounted on the wearer separate from the system.Thus, the system may be part of a portable/wearable computing device inthe form of separate devices that can be worn on or carried by thewearer. Separate components that make up the wearable computing devicemay be communicatively coupled in either a wired or a wireless fashion.In some further examples, additional functional and/or physicalcomponents may be added.

The system may be further configured to display images or visualelements to both eyes of the wearer Alternatively, the system maydisplay images or elements to only one eye, either a left eye or a righteye.

The system may include a gyroscope, a global positioning system (GPS),magnetometer, and an accelerometer. The faceguard can be configured toprovide information associated with a position and an orientation of thefaceguard to the processor. The gyroscope may include amicro-electromechanical system (MEMS) gyroscope or a fiber opticgyroscope as examples. The gyroscope may be configured to provideorientation information to the processor. The GPS unit can include areceiver that obtains clock and other signals from GPS satellites. TheGPS unit can be configured to provide real-time location information tothe processor. The faceguard can further include an accelerometerconfigured to provide motion input data to the processor.

Additional Embodiments

In one embodiment, the device or method uses utilizes a faceguard withan eye-tracking and measuring sensor, a head motion sensor and comparesthe gain and phase of each (e.g. an electronic circuit generates acomparison of the three axes from the head orientation sensing elementwith eye movement signals from the eye sensor to calculate a gain andphase of the eye movement response to head rotation, in the oppositedirection). The eye orientation sensor senses vertical movement andhorizontal movement of at least one eye. The faceguard could beconfigured for a microphone for voice commands, and at least 12 GB ofusable storage.

The faceguard can measure the relationship between motion of the head inthis environment and vestibular ocular reflex. The data acquired can beuploaded to a remote position from the user for display andinterpretation or transmitted wirelessly to a smart phone, wearabledisplay device or other hand-held device, or another computer source.Under normal circumstances, when measuring the VOR and the user islooking at a visual element, the head turns in one direction and theeyes reflexively move in the opposite direction to maintain fixation onthe visual element. The eye movement lags behind the head movement by 10ms or less. Eye movement responses longer than this would be abnormal.The head orientation sensor can sense pitch and yaw of the person's headin a range of frequencies that comprises at least one frequency greaterthan 0.01 Hertz and less than 15 Hertz. The head orientation sensor cancomprise an IMU. The head orientation sensor can comprise one or moreaccelerometer(s), magnetometer(s), and/or gyroscopes.

In one embodiment, a single camera system is used for the eye tracking.In another embodiment, a multi-camera system can be used and thecameras, attached to the framework elements, can be located in differentsight planes or at different distances from the measured area of the eyeor in a device attached to the faceguard, such as an iPhone or otherelectronic device. The camera control unit could be activated by ahaptic human input signal, by an auditory human input signal, by amanual input signal, by a pre-set timer, by measured impact thresholdswhich reach or exceed those pre-set thresholds for concussions, and/orby an external wireless signal. The camera could have a resolution of atleast five megapixels and could be capable of recording at 720p or 1080presolutions. The camera could support Bluetooth and/or Wi-Fi. The cameracould be part of, or work with an Android or iOS smartphone. The cameracould have at least a 25° field of view. The camera system could alsocomprise an onboard OMAP (Open Multimedia Applications Platform)processor running the Android or iOS operating system. The entire camerasystem could be a smartphone mounted or attached to a faceguard, thatincludes an embedded eye camera sensor with a head motion sensor.Providing direct image overlay over the wearer's main line-of-sight,coupled with the motion sensors and camera, it can enable true augmentedreality capability. A smartphone or similar device (such as a tabletcomputer) could also be used to provide wireless remote control.

In one embodiment, the eye-tracker uses the center of the pupil andinfrared and/or near-infrared non-collimated light to create cornealreflections (CR). The vector between the pupil center and the cornealreflections can be used to compute the point of regard on surface or thegaze direction.

In an alternative embodiment of a binocular system, two mirror-imageoptical systems are mounted on each side of the faceguard frame. Thecorneal reflections are generated by illumination with two infraredLED's mounted to the faceguard frame. These LED's also serve toilluminate the pupil. The use of infrared (IR) light allows forinvisible illumination of the eye. The use of multiple cornealreflections extends the linear range of the system by ensuring that onecorneal reflection is always visible on the spherical surface of thecornea even with eccentric gaze. The images of the pupil and cornealreflections are reflected off of an IR mirror positioned in front of thesubject's eye and directed to the cameras. This mirror is transparent tovisible light and thus does not interfere with normal vision. The videoimage is sampled by a custom charge-coupled device (CCD) array thatallows images to be sampled minimally at 20 Hz. Images from the CCDcamera are processed in real time to obtain estimates of the cornealreflection and pupil center locations. Calibration of the eye trackercan be performed using a light source projected in front of the user,such as a laser pointer, or other detailed natural object andcalibration procedure looking at multiple objects or points.

Testing of the VOR can also be tested with pitch and roll of the headtilt. Predictive tracking (e.g. algorithm which can predict the nexthead position and orientation can help computing and updating) can beused to prevent latency issues and lessen motion disturbances whilebeing tested. A bone conducting sensor incorporated in the framework canprovide haptic or auditory/acoustic signals to the user for cueing torotate the head or performing other tasks. This data can then be stored,logged, interpreted and uploaded to a remote location. The eye trackingsystem can be used with or without a light source.

Trackers can constantly ping the sensors in the IMU to get informationfrom them. The rate at which this happens is expressed as [samples] Hz(per second). The wearer of a head tracker may perform a gesture toindicate an attempt to unlock the head mounted camera display. Forexample, a gyroscope coupled to the faceguard may detect a head tilt,for example, and indicate that the wearer may be attempting to unlockthe head mounted display screen.

In one embodiment the head tracker comprises an IMU, a battery andwireless interface charger, a wireless interfaced micro-controller, anda transceiver. The gyroscope in the IMU can be capable of sampling ratesup to 760 Hz, and the transmitter link can have the throughput totransmit that fully under 1 ms latency to the remote station. Fullpositional updates (fused information from all the sensors) from the IMUcan be sent at a rate of at least 500 Hz. The IMU comprises sensors thatcan sense roll, pitch, and yaw, as well as inertia when the IMU is movedforward/back, left/right, and up/down. The IMU could be a nine DOF IMU.

The mounted head tracker sensor in the head worn/eye worn device caninclude an IMU of any type cable of being understood by anyone skilledin the art. The mounting of the head tracker can be located anywhere tothe faceguard and in any manner to the faceguard.

Another alternative embodiment of the invention is an inertial angularorientation tracking apparatus mounted to the faceguard. Drift sensitivesensors, such as angular rate sensors, produce a signal that isintegrated to give a signal that represents angular position. Theangular position signal may drift, due to integration of a bias or noisein the output of the rate sensors. To correct this drift, compensatingsensors, such as gravimetric tilt sensors and geomagnetic headingsensor(s) can periodically measure the angular position, and thisdirectly measured position signal is used to correct the drift of theintegrated position signal. The direct angular position sensors cannotbe used alone for dynamic applications because the gravitational sensorsare also affected by non-gravitational accelerations, and therefore onlyaccurately reflect angular position when under the influence of nonon-gravitational accelerations. Typically, the drift sensitive sensorsare angular rate sensors, (these include: rate gyroscopes and vibratingpiezoelectric, magneto-hydrodynamic, optical and micro-machined silicondevices) the outputs from which are integrated once. However, othersuitable drift sensitive sensors include linear accelerometers used tosense angular rate, gyroscopic angular position sensors and angularaccelerometers. Typically, the compensating sensors are inclinometers,accelerometers and compasses.

In another embodiment, the faceguard can be configured to include aposition tracker such as an acoustic position tracker, a system thattracks LEDs or IR position, optical sensors or reflective marks, a videomachine-vision device, sensors integrated in the faceguard or a radiofrequency position locating device.

In an alternative embodiment, the present invention not only measuresthe discussed ocular parameter, such as the VOR, but alsorehabilitates/retrains the user when an abnormality is present, toenhance the VOR and/or visual accuracy with specific visual stimulationand head movements. This rehabilitation can be done for specificvestibulo-ocular pathologic findings. Specifically, when there is anabnormal VOR in the horizontal plane, specific algorithms of eyefixation on a target object, while the head is moving horizontally canbe used to rehabilitate the abnormality. When the abnormal VOR is seenin the vertical plane, specific algorithms of eye fixation on a targetobject, while the head is moving in a vertical manner can be used torehabilitate the abnormality. As the VOR is enhanced or improved, theDVA or RIS will be enhanced and cognition can be improved.

In one embodiment, the device or method could provide a sound signaland/or visual signal to alert or provide cueing to the user to respondby moving the eye or head for testing of an eye muscle movementresponse. Remote sensing, using an attached electronic device to thefaceguard, such as a smart phone configured for eye and head tracking,can provide a visible target for testing eye movement characteristics inbroad daylight are all features that can be incorporated in embodimentsof the present technology. The faceguard system could also collect thedata, which could then be uploaded to a medical doctor, trainer, coachor other person at a remote location. This remote location could thenprovide verbal or visual feedback to the user and this feedback could beintegrated with other health status information provided to the user.

In one embodiment the device or method disclosed here can also be usedto help a person improve his or her VOR and DVS and accuracy used duringactivities in daily living, routine exercise, and high levelathletic/vocational activities. This can be used to help a personimprove his or her balance by challenging, exercising, enhancing, and/orretraining the VOR (fixation/re-fixation) used during activities indaily living, routine exercise, and high level athletic/vocationalactivities and therefore improving the ability to remain fixed on thevisual element or scene of interest. Thus, embodiments of the presentinvention can incorporate head movements in one or a number of planes aspart of a systematic program for enhancing the VOR and DVA. Using thefaceguard and methods described herein, it is possible forrehabilitation programs to incorporate head movement with stable imageidentification and image identification movement with the head remainingstable. The data obtained from the devices and methods described hereincan be used for wireless communications. The data can be embedded GIS orgeographic information system of the eyes or a digital map of where theeyes are located relative to the head movement.

In one embodiment, the device can be calibrated before it is used. Whenused in the laboratory setting, calibration can be performed by focusingon a distant target, such as a light bar or laser light which isprojected to the wall. The image or visual element moves horizontally,vertically and then is center located. Typically, several trials areperformed to establish reproducible results. During this test, theperson is instructed to rotate the head from side to side horizontallyor vertically to an auditory cue at frequencies ranging from 2 to 6 Hz.Eye movements are recorded including: direction, amplitude, and velocityof eye movements. Head inertial movements are recorded by the velocityrate sensor attached to the head. Tracking eye movement from spot tospot in this way is called “active tracking”. When used in anon-laboratory or a non-clinical setting, similar testing can beperformed if there are objects available to serve the same purpose asthe distant target in the laboratory setting. Testing of this typeallows gain, phase, and asymmetry to be measured separately at eachfrequency. A more sophisticated approach would be to ask the subject tofollow an object that is not necessarily moving at one specificfrequency, but at a combination of frequencies and then using a Fouriertransform to convolve the gain, phase, and asymmetry at variousfrequencies directly from the complex waveform that was being followedby the subject.

As described in the previous paragraph, in some embodiments of thepresent invention, the head movement tracked and measured can be active.Another approach is to use and measure natural movement that normallyoccurs during normal activities or activities associated with a person'swork and to compare that to the eye movement that occurs at the sametime using a Fourier transform. This approach can be called “naturaltracking” A third approach is to attach the head to something that thenforces the head to move in a specific pattern—which is called “passivetracking.”

In embodiments of the present invention, head movement testing can sensehorizontal, vertical or torsional movements at various linearvelocities, angular velocities, linear accelerations, angularaccelerations, or frequencies. Natural test method testing in thehorizontal plane could utilize focusing on a target moving across thehorizontal visual field. Watching a moving object ascend and descend inthe air can serve as a natural vertical test.

Any combination of the discussed embodiments of head inertial trackersand eye tracking systems can be used to measure the ocular response(e.g. VOR) with head movement. If active tracking is used, the uservisualizes a target of interest while moving the head. As the headmoves, the ocular responses can be tracked and measured by a variety ofmodalities. A Fourier transform or other method of analysis can be usedto compare the inertial head movement and eye muscle movement responseat various frequencies in a complex waveform and software can analyzethe data. The stored data can be displayed remotely and abnormalities ofthe related ocular response to the head movement can then predict theperformance of the user when performing an occupational activity.

In the prior art, clinicians have looked at the VOR response and made abinary judgment (e.g. the VOR was abnormal or normal). Thisnormal/abnormal criterion would then be used to determine whethervestibular rehabilitation was needed. A better method for evaluating theVOR response would be to measure vestibulo-ocular performance on acontinuous scale, just like we measure the speed of an athlete. By doingthis, one can get a subject's human performance measurement.Specifically, there can be a VOR response score that more clearlyestablishes the vestibulo-ocular response measurement and expresses thisresponse measurement in language that can more appropriately be appliedto human performance measurement and improvement. Establishing such ascoring system will enable people to more accurately predict humanperformance with specific activities. It may also help in thedevelopment of activities that improve the human performance in fieldswhere above average vestibular ocular performance is of benefit. Thesame use of scoring on a continuous scale and multi-frequency compositescoring can apply to DVA, DVS and RIS.

Areas of Application

Embodiments of the systems and methods described herein could be used ina variety of areas, including but not limited to the military, sports,medical, and commercial businesses. In the tests described herein, alloculomotor responses can be measured in a faceguard. Eye features andmovements, as well as eyelid, and head movements can be tracked. Eyemuscle movement responses, eye position, fixation ability, visualacuity, pupil function, vergence and cognition can all be easilymeasured with this technology in the faceguard. These eye parameters canbe correlated with movement of the extremities to assess hand eyecoordination. The faceguard can be attached to a helmet and used forprotection of at least part of the face when participating in potentialphysical contact activities including but not limited to football,lacrosse, hockey, horse-back riding, cycling, motor-cross, whitewater,climbing, baseball, construction or industrial applications and inhelmets used by security and/or military forces.

Sports.

Embodiments of the present invention, using ocular performancemeasurements, can be used in sports/athletic environments where ocularparameter measurement can help predict player performance, playerfatigue and early detection of abnormalities such as concussions andtraumatic brain injury. For example, if a player has an abnormal VOR/DVAin the horizontal plane, that person may not be able to catch a ballwhen competing in athletic activities that require the head to rotate ina horizontal plane. Similarly, if a player has a vertical VOR/DVAabnormality and is running downfield while looking upwards over theshoulder, the ball will not be in focus. Specifically, the retinalvisual stability and accuracy would be diminished. In this instance,there would a higher likelihood of dropping the ball compared to anotherathlete who has normal VOR responses with normal DVA. If a VORabnormality was determined to be present prior to play, which couldresult in difficulty with foveal fixation, and athlete could undergo VORretraining to rectify the abnormality and therefore improve playperformance. Alternatively, the coaching staff could select anotherathlete who did not have this abnormality. For example, on game day if afootball player had an abnormal VOR, with resultant decline in the DVA,in the vertical plane (e.g. lack of visual fixation on an object ofinterest with upwards and downwards movement of the head), then it canbe predicted that the athlete is not likely to catch a ball whilerunning downfield and looking upwards over the shoulder (e.g. you cannotcatch, what you cannot accurately see). This would offer some value tothe coaching staff in selecting plays for the player based on his/herpredicted performance. Additionally, if an athlete had such anabnormality and could be given some rehabilitation methods prior toplay, this could correct the abnormality and increase performance inthat activity. Athletes who have had concussions or TBI can have avestibular ocular performance (VOP) abnormality, with resultantdecrements in the VOR, DVA, or RIS. Embodiments of the present inventioncan be an accurate method to determine when the athlete is ready toreturn to play activities, based on improvement of the VOR or DVA. Ittherefore can be utilized in TBI/concussion evaluation/assessment andmanagement for return to play. It is also intended for athletes who wishto enhance their training and athletic/vocational performance. It can beused in fitness centers, sports training centers, athletic performancecenters, and vocational performance centers. Some ocular performancemeasurements, including VOR, can also be adversely affected by alcoholand drug use. Potential use of this testing can also provide a drugscreen for those individuals suspected of having suboptimal performance.Playing at higher performance levels demands excellent eye fixation onthe visual target of interest while they are in motion. If athleteswanted to perform at a higher level, it could change the culture ofadverse behavior activities, knowing that these activities would have anegative effect on their performance by having poor visual fixationwhile doing the activity they enjoy.

Military personnel functioning in a high-level environment and requiringtarget fixation of their eyes, while performing other activities such aswith head or body movement, require a normal VOR and normal DVA. If theVOR/DVA is abnormal, the individual will not demonstrate peak humanperformance. Embodiments of the present invention can be used by themilitary in places such as the pilot selection process or specialoperations community to aid in the selection of individuals without aVOR/DVA abnormality. VOP measurement could enable other individuals, whohad normal foveal fixation ability to be chosen for a particular taskthat has better predictable performance for a particular duty of theday. Like that discussed above with athletes, ocular performancemeasurements, including visual pursuit tracking and VOR, can beadversely affected by alcohol and drug use. This testing can provideevidence of military personnel suspected of having potential ofsuboptimal performance before performing specific duties requiring highperformance with eye fixation.

Medical.

Similarly, any person with a motion sensitivity disorder (such as motionsickness, vection induced motion sickness, or visually induced motionsickness) or a balance problem, either of a central or peripheralorigin, will have a VOR/DVA abnormality. Individuals with such anabnormality will express symptoms of dizziness, disorientation,difficulty with focusing, nausea, fuzziness, and such other complaintsas not being clear headed. Embodiments of the present invention can beuseful to people who have experienced a vestibular insult, vestibulardysfunction or labyrinthine dysfunction such as those caused byinfection, concussive injury, traumatic brain injury, vascular disease,ototoxic or vestibulotoxic medication use, surgical complications,Meniere's disease, people experiencing chronic imbalance, such as, butnot limited to, stroke victims, people with systemic illnesses, theelderly and other people who have experienced head injuries, especiallythose who have experienced cerebral or labyrinthine (inner ear)concussions. It also can be utilized other centers which performvestibular rehabilitation and athletic/vocational enhancementenvironments. This ocular performance measurement method using afaceguard, can be used as an objective tool for assisting in thediagnosis of traumatic brain injury (TBI), concussion and otherdegenerative cerebellar disorders that cause highly abnormal results.

Vestibular Rehabilitation. VOR scoring can also be beneficial indetermining who is likely to benefit with vestibular rehabilitationtherapy. VOR scoring can also be used more objectively in determiningthe benefit or improvement with such therapy. The system can includeimprovement information that can be used by the user, a coach, a medicalpractitioner, or any other advisor to help interpret the scoring andprovide advice and/or exercises to improve ocular reflex. Althoughvestibular rehabilitation therapy can improve the ocular responses, thisscoring can accurately quantify the improvement and more ably predictwho is able to return to their normal activity without loss of humanperformance. Having a VOP score can also provide feedback that helps tocontrol abnormal VOR responses. When an ocular response is abnormal withhead rotation (a VOR abnormality, for example), such a finding can alsodetermine a need for improvement with rehabilitation. Repetitive headmovement in the abnormal plane of rotation, while the eye remains fixedon a target of interest, can provide a means for improving or enhancingthe VOR or other eye responses. Specifically, if a VOR abnormality isfound to exist in the horizontal plane, VOR enhancement rehabilitationtherapy is given in the same plane. In this instance, the user focuseson a target of interest and the user rotates the head horizontally,while continuing to look at the target. If a VOR abnormality is found toexist in the vertical plane, VOR enhancement rehabilitation therapy isalso given in the similar plane of the abnormality. In this instance,the user focuses on a target of interest and the user rotates the headvertically, while continuing to look at the target. The head speed canbe varied and the target, which the user is focused, can be changed. Theprocess can be repeated as often as necessary until the VOR abnormalityis corrected. This therapy can be performed in any plane where such anabnormality exists. The same use of scoring on a continuous scale andmulti-frequency composite scoring can apply to DVA, DVS and RIS.

Embodiments of the inventions described herein can provide supernormalenhancement of these same systems where no balance disorder exists, asin the case for enhancement of athletic and vocational abilities.Embodiments can enable individuals to reach a higher level ofperformance in their occupation, enable them to have increased ocularperformance functions when participating in their usual occupational orplay activities as well as enabling cognitive training andrehabilitation. Such an enhancement methodology can be used inathletic/vocational enhancement or training.

Further Embodiments of the Invention

In another embodiment, an interactive ocular parameter program can beprovided that uses image-based interactivities for testing andmanagement of concussions/traumatic brain injury with periodicassessment to analyze the progress of cognitive deficits. A cognitiverehabilitative program can be used with specific identified cognitiveconditions. The cognitive testing can also be used for assessing theneurologic status, alertness, fatigability, return to play readiness,situational awareness, unhealthy status, predicting human performance,stress and managing any deficits detected with a visually interactivecognitive program designed to correct those deficits.

In another embodiment, this faceguard technology can be used in gamingactivities where multi-use players rely on observed measured visualaccuracy of ocular parameters to compete against each other.

In another embodiment, a hand-held device, configured to measure any ofthe ocular parameters described herein, can be attached to a faceguardand can transmit the measured data to a remote electronic device and tothe user. The hand-held device, such as a smart phone, iPad, or otherspecifically configured electronic device for measuring specific ocularparameters, can measure these responses using 2-D, 3-D, virtual realityor augmented reality system methods of display.

Collection of different imaging characteristics of the eye(s) canprovide better tracking ability of the eye movements. In anotherembodiment, one eye sensor within or attached to the faceguardstructural member, collects images of at least one part the eye(s) of auser and the same sensor collects images of different part of theeye(s). Alternatively, one sensor, within the faceguard structuralmember can collect images of at least one part of the eye(s) and anothersensor, within the faceguard structural member having a slightlydifferent focal length, can collect images of at least the same part, orof another part of the eye(s). Collection of different imagingcharacteristics of the eye(s) can provide better tracking ability of theeye movements.

In another embodiment, the eye sensor attached to the faceguard is animaging sensor or image sensor. Since the images received are at aminimum of 90 frames per second, the imaging sensor is not receiving astream of video, but rather is capturing single frames from the sensorand processing them single images. The imaging sensor type can include,but is not limited to infra-red, near infra-red, non-visual light,visible light, lidar, ultrasound and or combinations of different types.

In one embodiment, the present invention is comprised of an ocularperformance measuring system with head tracking and ocular-based sensorsintegrated into a face guard. The system described is configured formeasuring eye muscle movement responses and is comprised of at least oneeye sensor, a head orientation sensor and electronic circuit. Thissystem is responsive to a human generated input signal from the group ofbut not limited to an auditory human input signal, a haptic human inputsignal, a manual input signal. Alternatively, the system or otherconfigured components can also be responsive to input signals includinga remote input signal, accelerometer-based measures with pre-set impactthresholds, a digital auditory input signal, a digital haptic inputsignal, human eye muscle movement or a human gesture. As an example,eyelid closure, for a defined time, could also trigger theforward-facing camera. An algorithm measuring blinking time and durationto discriminate between voluntary and involuntary eye blinks could beused to issue an input signal to a controller to operate the camerasystem. The controller could communicate with other parts of the systemto support the commands.

In another embodiment—there can be different modes of detection or typesof input signals. For an on the field mode, this input control can bedesigned for use on the field of play. In this mode, testing isactivated using ‘triggers’ such as impact acceleration event usingpre-determined level and based on random timers. In another mode, thesideline modem, designed for testing and diagnostics, the testing canalways be on the tracking loop with a ‘look back trigger’ for certainevent thresholds which were measured. Embodiments can also have aUSB-mini connection to facilitate data transfer.

In another embodiment, two or more image sensors are configured in acomplementary fashion to increase sensor accuracy. Image sensors can beconfigured from the following group: image sensors of the same typeacross different focal lengths, image sensors of the same type acrossdifferent angular locations and/or image sensors of differing types toprovide composite images.

In an embodiment, the faceguard is attached to the helmet and has anaperture allowing the user to visualize the surrounding environment orscene. For some users, this aperture may be comprised of more structuralelements for facial protection, dependent on the player position. Otherplayers may have less structural elements protecting the face if morevisualization is preferred. The structural elements can be configured toprovide an aperture for unobstructed viewing of the surrounding scene.The aperture is configured to provide at least 10 degrees of viewing inall directions from a midpoint of the visual plane, when looking outwardinto the visual scene. The structural elements can be rigid to protectthe face and others may have some flexibility to help mitigate theimpacts to the facial structure and head.

Although the faceguard should be firmly coupled to the helmet, thefaceguard can be configured to have an adjustable interface, positionedbetween the faceguard and helmet. This would allow the faceguard to beused with different helmets.

In another application embodiment, the faceguard system can be used forgambling sports, fantasy football as well as other fantasy sports. Theocular performance measures discussed herein can provide informationabout player's health condition, including concussion, traumatic braininjury, neurologic status, cognition, fatigue, alertness, impairmentsand/or oculomotor parameter measurements to participants viewing thedata transmitted. Information acquired from the faceguard system can betransmitted to a mobile device, computer, or other electronic device ina variety of communication methods including a dedicated SMS textservice. Users of the devices can track athlete injuries, measure and/orpredict human performance of the athlete or team using the faceguardsystem. This data received can be used for draft assistance, measurementof play performance, predictions, injury assessments and as a measurefor duration of play.

In another embodiment, an interactive ocular parameter program can beprovided that uses image-based interactivities for testing andmanagement of concussions/traumatic brain injury with periodicassessment to analyze the progress of cognitive deficits. A cognitiverehabilitative program can be used with specific identified cognitiveconditions. The cognitive testing can also be used for assessing theneurologic status, alertness, fatigability, deployment readiness,situational awareness, unhealthy status, predicting human performance,stress and managing any deficits detected with a visually interactivecognitive program designed to correct those deficits.

In another embodiment, the faceguard system can be integrated withwireless systems and software, allowing the collection and analyzing ofreal-world eye tracking data from athletes on the field playing a sport.Mobile data logging allows the physiology data to be collected. Eyetracking metrics can also include gaze path, pupil diameter, blinkfrequency, heat map, areas of interest (AOI), moving areas of interest,fixations, fixations sequence, and dwells.

In another embodiment, the eye sensor can measure the pupil size; pupilmuscle movement, pupil movement velocity changes and/or duration ofpupil changes. These characteristics can be used to measure the healthstatus related to a concussion, traumatic brain injury, neurologicstatus and neurologic disorders, cognition, mental activity, alertness,fatigue, impairment due to drugs and alcohol and vision impairment. Italso can measure evidence of hearing loss, human behavior andsituational awareness.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. For example, the present invention may be used toprotect workers in an industrial setting, at a construction site, etc.In order to accomplish this, the device of the present invention may,for example, be attached to construction helmets. It is therefore to beunderstood that numerous modifications may be made to the illustrativeembodiments and that other arrangements may be devised without departingfrom the spirit and scope of the present invention as defined by theappended claims.

A number of variations and modifications of the disclosed embodimentscan also be used. The principles described here can also be used forapplications other than sports. While the principles of the disclosurehave been described above in connection with specific apparatuses andmethods, it is to be clearly understood that this description is madeonly by way of example and not as limitation on the scope of thedisclosure.

What is claimed is:
 1. A faceguard wherein: the faceguard is configuredfor measuring an eye muscle movement response; the faceguard comprises:a structural member configured for protecting at least one part of ahuman face; at least one aperture configured for human vision throughthe faceguard; an eye sensor wherein: the eye sensor comprises a videocamera; and the eye sensor senses eye information selected from thegroup of: eyeball movement; pupil size; and eyelid movement; a headorientation sensor wherein: the head orientation sensor senses a headmovement selected from the group of pitch and yaw of a person's headwherein pitch represents a rotation about a first axis representing upand down movement of the person's face when the rear of the person'shead moves in the opposite direction and yaw represents horizontalmovement of the face when looked at from the front about a second axissubstantially aligned with the spine and perpendicular to the firstaxis; and an electronic circuit wherein: the electronic circuitcomprises a central processing unit, and a memory unit; the electroniccircuit is responsive to the eye information received from the eyesensor; and the electronic circuit is responsive to the head movementinformation received from the head orientation sensor.
 2. The faceguardof claim 1 wherein: the faceguard is configured for attachment to ahelmet wherein the helmet is configured for being worn by a human. 3.The faceguard of claim 2 wherein: the interface between the faceguardand the helmet is adjustable.
 4. The faceguard of claim 1 wherein: thefaceguard is configured for measuring a human health condition selectedfrom the group of: concussion; traumatic brain injury; neurologicstatus; cognition; alertness; fatigue; impairment due to drugs;impairment due to alcohol; and vision impairment.
 5. The faceguard ofclaim 1 wherein: the eye sensor is below the inferior margin of theupper eyelid.
 6. The faceguard of claim 1 wherein: measuring an eyemuscle movement response further comprises a machine learning classifierconfigured for: identifying a pattern in response to an input imageframe from the video camera; and comparing the pattern to a targetpattern set.
 7. The faceguard of claim 1 wherein: the faceguard furthercomprises an impact sensor and an alarm wherein the alarm is responsiveto the impact sensor when an impact threshold has been reached.
 8. Thefaceguard of claim 1 wherein: the electronic circuit is responsive to asensor fusion algorithm.
 9. The faceguard of claim 1 wherein: theelectronic circuit further comprises a communication unit; and thecommunication unit is configured for wireless transmission ofinformation selected from the group of: the eye information; the headmovement information; and the measured eye muscle movement response. 10.The faceguard of claim 1 wherein: the electronic circuit is configuredfor generating an alarm signal in response to information selected fromthe group of: the eye information; the head movement information; andthe measured eye muscle movement response.
 11. The faceguard of claim 1wherein: the faceguard is configured for measuring and correctingslippage offsets between the faceguard and a helmet.
 12. The faceguardof claim 1 wherein: the faceguard further comprises a forward-facingcamera configured for recording video images at a minimum of 24 framesper second.
 13. The faceguard of claim 1 wherein: the eye sensor videocamera is configured for receiving images at a minimum of 90 frames persecond.
 14. The faceguard of claim 1 wherein: the faceguard furthercomprises a forward-pointing visual cue projector.
 15. The faceguard ofclaim 1 wherein: the head orientation sensor comprises amicro-electro-mechanical system integrated circuit comprising a moduleselected from the group consisting of an accelerometer, a magnetometer,and a gyroscope.
 16. A human ocular performance measuring systemwherein: the system is configured for measuring an eye muscle movementresponse; the system comprises: an eye sensor wherein: the eye sensor isaffixed to a faceguard wherein the faceguard comprises: a structuralmember configured for protecting at least one part of a human face; andat least one aperture configured for human vision through the faceguard;the eye sensor comprises a video camera; and the eye sensor senses eyemovement information selected from the group of: horizontal eyemovement; vertical eye movement; pupillometry; and eyelid movement; ahead orientation sensor wherein: the head orientation sensor is affixedto the faceguard; the head orientation sensor senses a head movementselected from the group of pitch and yaw of a person's head whereinpitch represents a rotation about a first axis representing up and downmovement of the person's face when the rear of the person's head movesin the opposite direction and yaw represents horizontal movement of theface when looked at from the front about a second axis substantiallyaligned with the spine and perpendicular to the first axis; and anelectronic circuit wherein: the electronic circuit comprises a centralprocessing unit, and a memory unit; the electronic circuit is responsiveto the eye movement information received from the eye sensor; and theelectronic circuit is responsive to head movement information receivedfrom the head orientation sensor.
 17. The system of claim 16 wherein:the system is responsive to a human generated input signal selected fromthe group of: an auditory human input signal; a haptic human inputsignal.
 18. The system of claim 16 wherein: [see paragraphs 171-173] thesystem is further configured to measure an eye parameter selected fromthe group of: bright and dark pupil measurements purkinje measurements.19. The system of claim 16 wherein: the system further comprises amodule configured for providing a visual cue that is visible to thehuman face.
 20. A method for measuring human ocular performancecomprising the steps of: establishing a faceguard that comprises: astructural member configured for protecting at least one part of a humanface, and at least one aperture configured for allowing human visionthrough the faceguard; an eye sensor comprising a video cameraconfigured for sensing eye movement information selected from the groupof: horizontal eye movement; vertical eye movement; pupillometry; andeyelid movement; a head orientation sensor configured for sensing a headmovement selected from the group of pitch and yaw of a person's headwherein pitch represents a rotation about a first axis representing upand down movement of the person's face when the rear of the person'shead moves in the opposite direction and yaw represents horizontalmovement of the face when looked at from the front about a second axissubstantially aligned with the spine and perpendicular to the firstaxis; and using an electronic circuit to: receive eye movementinformation from the eye sensor; receive head movement information fromthe head orientation sensor.